Hi Chandu,
Yes, it is an user status which is not allowing you to post GRN.
Please click i (Icon adjacent to WBS) and look for user status and do the changes accordingly.
OR
go to OPSA, look for "WBS sts. prof" under status management and find out the attached user status. Then, go to OK02 and find out your user status and do the changes there as per your requirement.
Regards,
Amit Rajoria