Reservation through MB21 with movement type 221


I am creating the reservation through Tcode mb21 with movement type 221 where i am putting the WBS ,material ,quantity and storage location .

Although budget is not available but reservation is getting created.

Steps :

Step-1--Creation Of project and WBS through CJ20n.

Step-2-Budgeting and budget release for Rs 5000.(tcode CJ30 and CJ32)

Step-3-Equipment has been created with respective WBS.Budget check is on place.

Step-4-PM order is craeted and actual cost has been posted for Rs 4000.

Step-5-Now i am creating the manual reservation through MB21 with movement type 221.Then system  is allowing to create the reservation more than available amount i.e 1000.