Connection Failure

Hello All,

My EP is connected to an R/3 system and I'm trying create an SAP RFC iView. I am able to put the function group name and get a list of functions available. But when I run this iView (via a role), I get a

"Function execution failed. Exception message: Nested Exception. Failure to execute native function. Connection Failed: Nested Exception. Native connection to the back end system is broken."

I am able to run this RFC fine via SE37. I also tried it using Visual Composer by creating a model with this RFC as the dataservice. I get a similar error

 Error during execution: Nested Exception. Failure to execute native function. Connection Failed: Nested Exception. Native connection to the back end system is broken.  

Can someone please tell me if this looks like authorization problem on R/3? Or something missing in my 'System' definition for R/3 in Portal?

Just to let you know, system connection (via "connection test") work fine in Portal for that R/3 system.

Thanks,

Kiran