jQuery selectable list inside a dialog widget

I am trying to implement a selectable and draggable list inside a
dialog widget. When the list is on the base page (outside of the
dialog widget) it works as expected. When I move it into the dialog,
the selectable nature disappears.
Any ideas why this is happening? Is there an overlay somewhere
blocking my click event on the list? I can't even trigger the click
event at all actually.
Thanks,
JL