Odata service is not triggering in get Entity set

Hi,

    I am working on a gateway service and I have created one RFC to expose data in Gateway service.

the input parameter in the FM Is UserId,IvSmodid IvModid IvAppid

based on that I am populating one table.

I used this RFC in Gateway service and my service URL is looks like below :

http://<HOST>:8000/sap/opu/odata/sap/<Servicename>/po_apprvalset(UserId2='VBHANOT',IvSmodid='PO_APPROVL',IvModid='PO_APPROVL',IvAppid='ZMOB_PO')

but this service is not getting triggered to Get entityset, everytime it triggers to Get Entity.

Can you help how to make it working for Get entity set also.

Thanks

Ram