I'm trying to activate a 'prev/next' function on the jquery plug in below but it's proving a tad difficult? where am i goin wrong

I'm trying to activate a 'prev/next' function on the jquery plug in below but it's proving a tad difficult? where am i goin wrong

Here is the html

<li>
 <a class='prev' href=''>previous</a>/<a class='next' href=''>next</a>
</li>

and here is the script

jQuery.fn.preload = function() {
    this.each(function() {
        jQuery("<img/>")[0].src = this;
    });
};

$(document).ready(function() {
    if (!$("body").hasClass("splash")) {
        return;
    }

    $('#video-bg').videoBG({
    position: "fixed",
    zIndex: -1,
    mp4: '/videos/splash/loop_intro.mp4',
    ogv: '/videos/splash/loop_intro.ogv',
    webm: '/videos/splash/loop_intro.webm',
        autoplay: true,
        loop: true,
    opacity: 1
    });

    $(window).resize(function() {
        $(".videoBG").css({
            width: $(window).width(),
            height: $(window).height()
        });
    });
});

$(document).ready(function() {
    if (!$("body").hasClass("home")) {
        return;
    }

    var e = $("#home0, #home1, #home2"),
        a = 0,
          c = ["images/ipanema/1.jpg",
             "images/ipanema/2.jpg",
             "images/ipanema/4.jpg",
             "images/ipanema/5.jpg",
             "images/ipanema/7.jpg",
             "images/ipanema/8.jpg",
             "images/ipanema/9.jpg",
             "images/ipanema/10.jpg"];

    e.hide();
    e.first().show();

    $("#description").html(e.first().find("span").html());

    $.backstretch(c[a], {
        speed: 1000
    });

    $(c).preload();

    imgswitch = function() {
        a = $active.attr("rel");
        $("#slider-controls a").removeClass("showing");
        $active.addClass("showing");
        e.fadeOut(1000).hide();
        $.backstretch(c[a]);
        $("#home" + a).fadeIn(1000).show();
        $("#description").empty().hide();
        $("#description").html($("#home" + a).find("span").html()).fadeIn();

    };

    rotateSwitch = function() {
        play = setInterval(function() {
            $active = $("#slider-controls a.showing").next();
            $active.length === 0 && ($active = $("#slider-controls a:first"));
            imgswitch();
        }, 4000);
    };

    $("#slider-controls a").click(function() {
        $active = $(this);
        clearInterval(play);
        imgswitch();
        rotateSwitch();
        return !1;
    });

    rotateSwitch();
});

$(document).ready(function() {
    if ($("body").hasClass("splash") ||
        $("body").hasClass("portfolio")) {
        return;
    }

    $("a.floorplan").live("click", function(e) {
        $.backstretch("/images/ipanema/floorplan.jpg", { speed: 1000 });
        e.preventDefault();
    });

    var imgs = $("#slideshow img");

    $(imgs).each(function() {
        $([$(this).attr("src")]).preload();
    });

    var current = 1;

    $("#slideshow").hide();

    var slideshow = function() {
        var current = 1;

        var updateControls = function(current) {
            $("a.load-slide").removeClass("current");
            $("a.load-slide[rel=" + current + "]").addClass("current");
        };

        return {
            next: function() {
                if (current == imgs.length) {
                    current = 1;
                } else {
                    current += 1;
                }

                $.backstretch("/images/ipanema/" + current + ".jpg", { speed: 1000 });
                slideshow.load(current);
            },

            prev: function() {
                if (current == 1) {
                    current = imgs.length;
                } else {
                    current -= 1;
                }

                slideshow.load(current);
            },

            load: function(i) {
                if (i == -1) {
                    i = current;
                }

                current = i;
                updateControls(i);
                $.backstretch("/images/ipanema/" + i + ".jpg", { speed: 1000 });
            }
        };
    }();

    $("next").live("click", function() {
        slideshow.next()
        e.preventDefault();
    });

    $("prev").live("click", function() {
        slideshow.prev()
        e.preventDefault();
    });

    $("a.load-slide").live("click", function(e) {
        slideshow.load(parseInt($(this).attr("rel"), 10));
        e.preventDefault();
    });

    $("a.description").live("click", function(e) {
        $(this).parent().addClass("current");
        $("#description").html($("div.description").children().clone());
        slideshow.load(-1);
        e.preventDefault();
    });



    slideshow.load(1);
});

// portfolio navigation
$(document).ready(function() {
    if (!$("body").hasClass("portfolio")) {
        return;
    }

    var apartments = {
        ipanema: {
            originalLocation: 890,
            location: 890
        },
        aproador: {
            originalLocation: 920,
            location: 920
        },
        copa: {
            originalLocation: 1260,
            location: 1260
        },
        chopin: {
            originalLocation: 2286,
            location: 2286
        },
        urca: {
            originalLocation: 5300,
            location: 5300
        }
    };

    var currentApartment = 'ipanema';

    var markers = {
        ipanema: {
            bottom: 380,
            height: 248
        },
        aproador: {
            bottom: 358,
            height: 270
        },
        copa: {
            bottom: 351,
            height: 277
        },
        chopin: {
            bottom: 528,
            height: 101
        },
        urca: {
            bottom: 467,
            height: 162
        }
    };

    var timer;

    $(window).resize(function() {
        if (timer !== undefined) {
            window.clearTimeout(timer);

        }

        timer = window.setTimeout(function() {
            $("#coast-line img").css({
                height: $(window).height() - 120 // 120 is height of the footer
            });

            $.map(apartments, function(element, index) {
                var location = element.originalLocation * $("#coast-line img").width() / 6500;
                apartments[index].location = location;
            });

            newMarginLeft = 0 - (apartments[currentApartment].location - ($(window).width() / 2));

            $("#coast-line img").css({
                marginLeft: newMarginLeft
            });

            // markers
            // bottom
            $("#ipanema-marker").animate({
                left: apartments.ipanema.location - Math.abs(newMarginLeft),
                bottom: markers.ipanema.bottom * ($(window).height() - 120) / 840
            }, 250);

            $("#ipanema-marker #ipanema-bar").css({
                height: $("#coast-line img").height() * markers.ipanema.height / 840
            });

            $("#aproador-marker").animate({
                left: apartments.aproador.location - Math.abs(newMarginLeft),
                bottom: markers.aproador.bottom * ($(window).height() - 120) / 840
            }, 250);

            $("#aproador-marker #aproador-bar").css({
                height: $("#coast-line img").height() * markers.aproador.height / 840
            });


            $("#copa-marker").animate({
                left: apartments.copa.location - Math.abs(newMarginLeft),
                bottom: markers.copa.bottom * ($(window).height() - 120) / 840
            }, 250);

            $("#copa-marker #copa-bar").css({
                height: $("#coast-line img").height() * markers.copa.height / 840
            });

            $("#chopin-marker").animate({
                left: apartments.chopin.location - Math.abs(newMarginLeft),
                bottom: markers.chopin.bottom * ($(window).height() - 120) / 840
            }, 250);

            $("#chopin-marker #chopin-bar").css({
                height: $("#coast-line img").height() * markers.chopin.height / 840
            });


            $("#urca-marker").animate({
                left: apartments.urca.location - Math.abs(newMarginLeft),
                bottom: markers.urca.bottom * ($(window).height() - 120) / 840
            }, 250);

            $("#urca-marker #urca-bar").css({
                height: $("#coast-line img").height() * markers.urca.height / 840
            });

        }, 500);
    });

    setTimeout(function() {
        $(window).trigger("resize");
    }, 500);

    $("a.ipanema").click(function(e) {
        e.preventDefault();
    });

    var links = "a.ipanema, a.aproador, a.copa, a.chopin, a.urca";

    $(links).click(function(e) {
        var apartment = $(this).attr("class").split(" ")[0];

        var newMarginLeft = 0 - (apartments[apartment].location - ($(window).width() / 2));

        $("#coast-line img").animate({
            marginLeft: newMarginLeft

        }, 1000, function() {
        });

        $("#ipanema-marker").animate({
            left: apartments.ipanema.location - Math.abs(newMarginLeft)
        }, 1000);

        $("#aproador-marker").animate({
            left: apartments.aproador.location - Math.abs(newMarginLeft)
        }, 1000);

        $("#copa-marker").animate({
            left: apartments.copa.location - Math.abs(newMarginLeft)
        }, 1000);

        $("#chopin-marker").animate({
            left: apartments.chopin.location - Math.abs(newMarginLeft)
        }, 1000);

        $("#urca-marker").animate({
            left: apartments.urca.location - Math.abs(newMarginLeft)
        }, 1000);


        currentApartment = apartment;

        $(links).removeClass("prev")
            .removeClass("next")
            .removeClass("current");

        $(this).addClass("current");

        var prev = $(this).prev().length ? $(this).prev() : $("#portfolio-controls a").last();
        var next = $(this).next().length ? $(this).next() : $("#portfolio-controls a").first();

        console.log(prev);

        $(prev).addClass("prev");
        $(next).addClass("next");

        e.preventDefault();
    });
});

if ((navigator.userAgent.match(/iPhone/i)) ||
    (navigator.userAgent.match(/iPod/i)) ||
    (navigator.userAgent.match(/iPad/i))) {

    $("#navigation li").click(function() {
        //we just need to attach a click event listener to provoke iPhone/iPod/iPad's hover event
        //strange
    });
}