Dynamic Action to default Known as to First Name in IT0002

I wrote the below dynamic action to default Known as to First Name but somehow it does not work. This default should happen upon create/modify of IT0002. Can someone please guide me towards my mistake:

0002

04 116 P PSPAR-WERKS='XYCD' 0002

04 118 I MOD,0002 0002

04 120 W P0002-VORNA=P0002-RUFNM