I had a look on the schulze homepage, and the kw is listed under the esc's without bec:
http://www.schulze-elektronik-gmbh.de/futu-d.htm
So I am pretty sure, too, that you need an external bec/Ubec to run the esc. without, you have no power for the esc, the receiver and so on.
edit
oops, just saw that youre using a ubec... mabe a problem w. the ubec?