hi Ashish,
Please check table T006 for PC.. It might give you an entry as ST. Edit your data to take ST in place of PC, and try to reactivate. Reference: http://scn.sap.com/thread/2023820
Or if you do not see the entry at all, you will have to go to RSA1 -> source systems -> right click -> transfer global settings.
Hope this helps!
Thanks,
Sheen