Hello Shailesh,
You need to define a property as Key in your model which is one among a field present in the out response of the table which you would like to map back as GW response..
i.e., which ever tables of the FM your are mapping as output response, pick any one property from that table and define it as a key.
This will resolve the error.
In your case make PurchNo as Key and check.
Regards,
Ashwin
