Status Profile - Restrict any changes made in sales document

Hi SD Guru's

I have a situation here. I have maintained status profile with one of the status as "REJ - Reject Sales Order". Now when i set that status "REJ" and save the order, and open it by transaction VA02, i can make any changes in the order document such as adding new line item. I want to restrict any changes for this order now. How can i tackle this situation. Can you please help me with the same, its urgent.

Regards

Ravi