Validation for FBCJ

HI SAP,

What logic must give in check filed in validation for " Back date posting not allowed for Cash book FBCJ" ??

I assiged in prerequest as " transaction code=FBCJ"

and in check == i assgned as Document date =current date or posting date =current date

and in messge --back date not allowed for cash

but above validation not working fine. how to do??

Regards,