Drag and drop problem: i am out of ideas

Hi, i created a calendar applications with dropable appointments, and i
works fine but only once. after a remote update it doesn’t work anymore.
I looked at the generated source (DOM) and it looks ok, even if i copy
this source into a static html doc, it works again, so this is very hard
to debug.
does anyone have a clue of what could be the problem here?
even a direction of where i can look would be great.

i am so close of having a great calendar, but i cant take this step

thanks

Remco