Inconsistency of values in MR11

Dear All,

Below error occurred when I am trying to do GR/IR maintenance in MR11 for delivery charges.

Please help me to fix this error.

Purchase order Quantity- 300

Goods receipt- MIGO :-

Freight Invoice receipt- MIRO :-

Note:- SAP did not posted any values to inventory account for this difference in MIRO

GR/IR clearing account maintenance- MR11:-

Quantity Received Quantity invoiced     Difference Qty   Difference Value              CTyp

           298                           300                          2-                 61.90                           ZMSC

Error:-

Purchase order history already inconsistent --> Quantity                2.000- EA Value               61.90

Message no. CKMLGRIR025

Diagnosis

The purchase order history contains differences between the goods receipts  and invoice receipts/Account maintenance for the order item in fields  Difference Quantity (=               2.000- EA) and Difference  value (=               61.90).

The purchase order history for this item is inconsistent

System Response

This purchase order item will not be processed.

Procedure

Inform your System administrators.

Thanks,

Krishna samy