Data validation: Specific value only possible if other Columns filled

Dear Community,

OK - Robot status should only be possible to be saved if KOB, RATING and ERP is filled out.

How can I do this through data validation or is there a better way to do it?

Ive created a helper column called Filled: =IF(OR(ERP="";KOB="";RATING="");FALSE;TRUE)

But I dont know if its possible to restrict one status only to be possible if this helper column is "True"