Communication failure in RFC

Hi,

I am currently doing an RFC call to a FM using "Call function Destination XXX".

But i am getting the communication failure exception raised.

Unfortunately i do not have the authorisation to SM59 to check further.

I tried checking if the RFC was set for this destination system.

I did a remote comparison for a report from source system to target system and it asked me to manually logon.I enetered the login details and could successfully do a comparison there.

But i still get a communication failure while doing a RFC cal to this FM.

Can somebody please help?