Outbound que stuck from APO to ECC-account assignment error

Hello,

outbound ques are failing (only for four materials ) . The error is "account assignment mandatory for material,xxxxxxx. (enter account assignment ) " . PR (STR)  are t/f  from APO to ECC. we have our own Z material type .

for the Z materials, accounting view is not maintained in ECC. Plus for all the plants in ECC, "value updating " is not checked in ECC in OMS2 T code.

Pls suggest how to resolve the error ?

regards

Pamela