Unable to call RFC

Hi,

I'm working on a web dynpro application that involves ARFC calls. After deploying this application to portal, I'm able to call the backend BAPIs with some users but not with all. I tried assigning the Super Admin role to one test user to check whether it solves the problem, but it did not.

What could be the issue here? Something to do with JCo. I'm using uid/pwd for logging on to backend abap system.

Any pointers are appreciated.

Thanks,

Vishwas.