Curreny Problem in F-53

Hello All

I Have Booked One JV as under.through F-43 Exchange Rate is 42.0325 EUR to THB.

Vendor Account Cr P.K 39 400 EUR Local Currency Amt is 16813/- ( THB )

Vendor Account Dr P.K 29 A 400 EUR Local Currency Amt is 16813/- ( THB).

Now i am going to make payment through F-53 in local currency.(THB )

When i click process on open item system shows me 16580/- instead of 16813/- i am not getting that why this amount is come.

There is one I-con which name is ''currency'' when i click that then system shows me 16813/-. i wonder from where system pick 16580/- .

When i simulate the Transaction System Show me Amount 16813/- In Local Currency and 16580/- in Document Currency.

I wonder that how i can system show me different amount for same currency

Manoj J