Problem destroying draggable

Using jQuery 1.3.2, I see the following error when trying to
call .draggable('destroy') on ui.draggable within a droppable's drop
function:
$(this).data("draggable") is undefined
var o = $(this).data('draggable').options; ui.draggable.js (line
565)
Any ideas what I'm doing wrong?
- Bobby