Problem with a number iteration

I already did did this kind of operation with your help. I create an iterate number like that : yyyymmdd00001....

I would like to do a new one for another number field. I write exactly the same script of the other one and it dosn't work. When I submit, a message appears and tell that "invalid entries was found". I don't undesand the problems, that's now few days that i'm blocked with that.

Can you help me please? You can access my application.

Thank you!