Basis - Feild Exit Not Triggering For Some Users

Hi Experts ,

I have created a feild Exit For MKPF-BUDAT (FEILD_EXIT_BUDAT), for restricting use of back date in MB31 by users.

It's working fine for most of the users , but for some users that feild exit is not triggering at all .

Please help me how to tackle this .

Thanks & Regards ,

Rajesh