In f-28 system debit foreign exchange diff. gl instead of Bank G/L

Dear Experts,

I have an urgent issue, during customer payment through transaction code F-28, System post foreign exchange difference Gl instead of bank account.

Ex: The posting should be :

Bank (Incoming G/l) account DR

To Customer A/c Cr

--------------------------------------------

But , system posting: Foreign exchange diff G/L a/c Dr

                                        To Customer A/c Cr

                                        ------------------------------------------

please reply on this issue as it is most important.

regards,

S.Singh