Payment journal for Service Tax POT in Foreign Currency

Hi All,

I have been trying to post a Payment journal ie. receipt from a customer with

Serv. Tax on Advance Payment :- YES.
POT :- YES
Amount :- 1000
Currency Code :- USD (exchange rate 50)

Following G/L got Posted

Bank A/C

---

> Dr 50000/-
Customer A/C

---

> Cr 50000/-
Service Tax Payable I ----> Cr 269,500/-
Realized FX Losses

---

> Dr 269,500/-
Service Tax Payable I ----> Cr 5500/-
Service Tax Payable Interim--> Dr 5500/-

The PAyment is a Advance Payment and has not been applied to any Invoice.

Not able to understand the logic of posting the Realized FX Losses A/c with Rs 269,500/-


regards,
APS