Purchase requisition assigned to other order account

Dear All,

I came across a purchase requisition issue , when i try to create an MRP purchase order based on purchase requisitions created. The system at the point of transfers the purchase requisitions into the ME51N cart prompts the below mentioned message

"Purchase requisition assigned to other order account"

What could be the possibe reason as to why this is happenning. I checked in the system with that particular mentioned requisitions is available in the system and am unable to find it.

Shall await your thoughts on this.

Thanks & Regard

Shabeen Buhary