Through the error message when the costing done from the T-code iwa51

Hello,

costing is done thorough the T-code iw51 and change iw52.

Now I want to through the error message when the costing done from the T-code iwa51 and Iw52.

Is there any exit.  But costing should be possible in the tcode VA02. I want restrict only for the tcode iw51 and iw52.