Non sap system triggered below Request XML format but facing issue at prefix in body

Dear Experts,

I have been trying to solve below issue but not able to complete the requirement,could you please help on this issue.

Working on PI 7.5

Below XML format triggering from Non sap and I have done scenario Rest to RFC as synchronous scenario(Nonsap to PI to Sap).End point URL (REST API-POST) given to third party.

Below Request From third party-

If I test the integration by postman tool using below XML format message then After Message(AM) payload not generated (Could see BI & MS payloads) in message monitor if I check message log getting error "InterfaceDetermination did not yield any actual interface".

<?xml version="1.0" encoding="UTF-8"?> <permittLetterGeneration xmlns:ns2=

"http://kyc.com"

> <REF> <Aut>NI98</Aut> <Num>KLM</Num> </REF> </permittLetterGeneration>

If I try below format message delivered successfully but I need to do process as above request format.

<ns2:permittLetterGeneration xmlns:ns2=

"http://kyc.com"

> <REF> <Aut>NI98</Aut> <Num>KLM</Num> </REF> </ns2:permittLetterGeneration>

Facing issue at prefix if I keep prefix infront of the permittLetterGeneration then message processed otherwise getting 500 internal server error in postman tool and "InterfaceDetermination did not yield any actual interface" error in PI.

Please suggest me.

Thanking you sir