Service Tax on Down payment is also getting cleared when clearing Customer

Hi,

when i pass down payment the entry is as follows

Bank A/c Dr 10000

Customer A/c Cr 9000 (Special GL)

Service Tax A/c Cr 1000

When i clear the down payment against invoice the entry is as follows

Customer A/c Dr 9000 (Special GL)

Service Tax A/c Dr 1000

Customer A/c Cr 10000

But i should clear only 9000 not 10000. and service tax also should not get reversed when clearing doc.

And could not find any specific configuration in resolving the above issue.

Please provide any help on resolving the above issue.

Thanks and Regards,

G VINOD