Hi Vivek,
As a first level check, see if you can login to your ERP system using the same credentials. If you can, then enter t-code SE37, enter the RFC name, then click on the pipe wrench icon (test) and see if you are allowed to test the RFC. There are likely another level of authorizations needed even if you get this far, but it is a good check.
And as Amit mentioned, you need to have your RFC remote enabled as well as the right authorizations. A Basis or Security person will likely be needed if there is a problem with any of this.
Regards, Mike