OData Service Create_Entity Issue while testing from Gateway Client

Dear Friends,

I have a OData Service with Create_entity method to insert a record. Getting error while testing from Gateway Client, please find the attached error screen and suggest me. odataserviceerror.jpg

Method: Post

URI: /sap/opu/odata/SAP/ZHCM_SR_CREATE_SRV_SRV/CREATESRSet(Srqno='1000000000')

Error: The specified HTTP method is not allowed for the resource identified by the Data Service Request URI

Thanks,

Prasad.