Search: A discrepancy exists between the sales order and its corresponding internal requisition

Hi ,

When I try to cancel the line of a internal sales order I am getting error message

A discrepancy exists between the sales order and its corresponding internal requisition

The quantity in sales order line and requisition line matched but the requisition quantity and delivered quantity differ.

Can any one suggest how to cancel this line in internal sales order line.

Thanks

Tanmoy banerjee