[jQuery] $(html) error...I think. Please help, I'm stumped!

[jQuery] $(html) error...I think. Please help, I'm stumped!


Hello everyone! My name is Dustin and was hoping I could get a little
help with a JQuery problem I've run into. I just started using JQuery
and have been trying out a little AJAX when I ran into a problem. In
Firefox (using Firebug) I get the error:
ret[i].getElementsByTagName is not a function
r = jQuery.merge( r, ret[i].getElementsByTagName( tag ));
Here is my Javascript code where the error appears to be.
        $.ajax({
         url: 'CS_AJAX_Server_Responder.cfm',
         type: 'POST',
         dataType: 'html',
         timeout: 30000,
         data:
{Invoice:invoiceNum,Store:storeNum,Div:divNum,invoicevalidate:'true' },
         error: function(){
             $('#loadingimg').fadeOut("slow");
         alert('Error accessing server. Please try again.');
         },
            success: function(html){
                $('#loadingimg').fadeOut("slow");
                alert('test message');
             $(html).find('#invoice').each(function(){
             var invalidDiv = $(this).text();
                    alert(invalidDiv);
             });
            }
        });
    }
}
My server side code is very simple.
<ul><li id="invoice">invalid</li></ul>
The error appears to be caused by $(html).find() but I really do not
have a clue as to why. Once I remove the $(html).find() code it no
longer throws the error. The frustrating thing is that I had
everything working yesterday but it does not work any longer and I
have no idea what I changed that could have led to this error. In IE I
don't get any error but it doesn't proceed through the code like
normal. Please, any insight and help would be appreciated...this has
been driving me up the wall.