sold to party showing editble mode in sales contract

Hi all,

I created a sales contract and followed by sales order, delivery billing the movement i am checking sales contract SOLD TO Party its showing editable mode in contract over view screen and i check in header partners it showing sold to party in gray mode , i maintain relevant configuration ( partner determination i mark as a SP not editable and mandatory function in sales document header and procedure KAB release order in that i assign SP sold to party with not editable and mandatory function

still its showing editable mode in sales contract

Same Config is working fine for Sales order, once subsequent document is created sold changing into gray mode

why same confg is not working for Sales contract

can any one guide me where i am wrong

Thanks

Rajesh