SAP Message TU262 - Payment schema amount &1 (&3) is smaler than billing amount &2

Diagnosis
You changed amount &V1& for due date &V3&. It is now smaller than theamount of basic billing document &V2&. This is not permissible.

System Response
The amount for due date &V3& is not changed.

Procedure
You can reduce the amount for due date &V3& to no lower than &V2&.