Facing Problem with subscription Execution?

Hi,

We have a service which updates a single entry in a data table.Which works prefect when test it on service level.

Where as I execute the same service in a subscription on data change of the property, it inserts new record (with single value and remaining column entries are blank) in data table instead of updating the existing one.

Could anyone help us to resolve this issue?

Thanks in advance

Thanks

Anil Kesana