Dialog not positioning at all

Dialog not positioning at all

Help, I'm losing my mind!  I am creating a new UI dialog and am just trying to position it with the "position" option.  I tried any permutation (mentioned in the manual) - none works.  So I use Firebug to walk through the code and am now even more confused.  My jQuery UI code calls jQuery.position like so:

       this.uiDialog
            // workaround for jQuery bug #5781 http://dev.jquery.com/ticket/5781
            .css({ top: 0, left: 0 })
            .position({
                my: myAt.join(' '),
                at: myAt.join(' '),
                offset: offset.join(' '),
                of: window,
                collision: 'fit',
                // ensure that the titlebar is never outside the document
                using: function(pos) {
                    var topOffset = $(this).css(pos).offset().top;
                    if (topOffset < 0) {
                        $(this).css('top', pos.top - topOffset);
                    }
                }
            });

The values in the parameter object all look alright but jQuery.position() does not take any input arguments:

    jQuery.fn.extend({
        position: function() {
            if ( !this[0] ) {
               return null;
           }

          ...

How is this supposed to work?  I am running jQuery UI 1.8 and jQuery 1.4.2

Does anyone have any suggestions?  Thanks.