Ok, got it to work now.
I did like this, recreated the update via Data wiz.
Renamed the text-form for the file location too "hidden" (as i read here somewhere, as i hade done in the old file that didnt work)
Keept the value intakt on the hidden-form, added a file-form and renamed the ID.
Added the behaviors and gave it a shoot. And it worked!! :)
So in the end i think i missed something on my first 20 trys and in a need of a wigg atm.
The SQL error i had maybe hade something todo with it also.