Hi Srinivasan,
Also, on Netweaver Gateway, goto transaction and expand till SPRO->SAP Netweaver->Gateway-> OData Channel Developement with IW_BEP -> Service Validation and execute Validate Service
In the service documentation Identifier, please provide : ZEXPENSEREPORT_0001
and execute it will provide few more information about the errors
Regards,
Srinivas Divakarla