Hi Sheetal,
I assume that the RFC destination that has been used to define the Gateway alias in the customizing is not correct.
Please check my quick starter guide:
http://scn.sap.com/docs/DOC-41416
Instead of "NONE" the RFC destination should point to your Gateway hub system where IW_FND and GW_CORE have been deployed.
You can check this using transaction SM59 in your backend and try to perform a remote logon. You should end up in your hub system.
Though this should be fixed you should be able to activate the service from your hub system by running transaction /IWFND/R_MGW_REGISTRATION and press "add service".
