Restricting Goods issue quantity greater than Planned qantity in PS

Hi,

I have the following Client Requirement.

When issuing the Goods against the Network/Activity, system should not allow the user to issue goods more than the Planned quantity in Project System.

E.g., Material Code : 1000001

Quantity in PS against activity 0015 is 10 Nos

Goods issue against the Activity is 12 Nos(the two nos were actually planned and received for some other activity)

Is it possible to Restrict the user from doing so.

Please suggest.

Thanks.