Backend Error : SO1030000: quantity entered (2,000) exceeds target value 1,000 in contract

Purchasing Value contract for services exist in SRM. However when try to purchase more than one quantity above error occurs although the value has not reached its target value. I have tried simulating in S4 Hana as well and following error message occurs " Quantity entered exceeds target quantity in contract (message no. SE346)" appears. I'm not sure why such error happens for a value contract.

Please do let me know if more details needed as my first time posting and I'm new to SAP. Appreciate kind assistance from members.