[TYPO3] problem with [Gobernalia] AJAX Backend Drag And Drop

[Chris Kievid]

I used [Gobernalia] AJAX Backend Drag And Drop extension with succes on 
my localsystem, but now the same extension does not work on an exact 
live copy (both typo3 4 beta3 installs). The moving of CE's ain't 
working, instead I see this: (the black dot, plus an offset of the CE

http://img384.imageshack.us/img384/3964/ajaxproblem8zb.gif

Any ideas what's causing this?

cheers