Pricing routine scenario

Hi all,

My requirment is when we creating the purchase order (ME21N tcode) , if the Incoterm is 'ZOP' then the condition type 'ZF51' ( It is manual condition type ) will automatically appear in the condition block otherwise it should not be there in the screen and if the user really wants the condition type then the use can include the ZF51 ( Because the user intentionally wants this condition type we should not ristric ).

For this requirment i have created the pricing routine for this condition type and i wrote code also. But my problem is like this, for the first time i have given the incoterm 'ZOP' then our condition type will appear in the screen and then i am removing the incoterm. so, actually ZF51 condition type should be remove in the condition block but it is not reflecting the changes.

what to do can any body telme the reason.

Thanks,

Mahi.