SOST msg "Document changed due to security requirements"

Hi,

        I am converting a smart form into HTML and sending that content as body of the email. I am able to send and check in SOST TCode in my IDES system.  But when in do the same in my Development system, mail send successfully and i can see that in SOST. But when i try to diplay the mail i am getting a msg  "Document changed due to security requirements"  in SOST.

        What might be the problem... Can any one Plzzz... !

Regards

Avinash.