error while creating Delivery

Dear team,

My requirnment is as follow...

I have a stock of 100 unit of material. I am creating sales order for same material for 50 unit. Here i have activated availability check with 02-individual requirment in material master. In sales order i have confirmed the quantity of 25 unit only.

Now my requirment is that system should not allow me to do PGI more than confirmed quantity (i.e. 25 in this case). How can i do this ??..currently system is allowing to do PGI upto 50 unit. I want to stop this.

thanks

tarpan vadalia