Quantity not updating in contract after putting rejection in Sale order

Dear SAP Champs

I have made a contract of 300 Qty and three different Sale order with 100 each and the first 2 sale order has been delivered, issued and billed with 100 each but in the third sale order which is of 100 qty only delivered with 50qty and issued 50 and billed with 50 qty and now we are putting reason for rejection for the third order which still have 50 qty left...

Now what happening

when I am checking line item wise third sale order flow status it is showing status completed but qty as 0. but here we have deviled 50 so why its showing 0 qty

secondly the status of contract becoming being possessed but when we are making new sale order with that contract its saying only 0.qty left

Please help....