Creation of PO against contract.

Hi all, When am trying to create PO with exactly equal quantity as of contract, system is giving following msg.

" Contract target value 4603000837 reached". I checked in system message settiing where this msg is marked as error msg. Also I checked in SE91 for msg class 06 & msg no. 155, where it shows as 'Contract target value & reached"

But my question is why system is giving this msg when its PO quantity is equal to contract target qty. What shud be the setting. If I set this msg for warning, then system will allow for exceeded Po qty also, which I dont want. Pls guide.

Regards,

Sarang