Thank you for the hint !
After applying the patch I was too dumb to activate the application for the user... After doing so, I always got "No SyncML response" on my cell phone. Checking the sync-logs I found out that something was wrong with the egw_syncml-tables. So I just emptied them manually and now it works fine. (Just if anybody has the same problem in the future...)
Thanks again, I am happy to have a working sync-solution now :-)
