In MM06E005 PO Customer Exit not allowing to change Screen exit.

Hi All,

I need to dislpay PO release date in Purchase Oder For that I have changed the Function Exit.Now for displaying purpose I m trying to change the SAPMM06E 0101 CUSTSCR1 SAPLXM06 0101

screen exit. It's throwing an error :

Function Group with Customer Include: Customer Par

contains inactive components

Please provide solution for the above problem.

Regards,

Nivedita.