Error in establishing Trust relation between two systems

Hi Experts,

I am facing below error while configuring trust sytem relation between two systems.

Error:

SMT1-- Authorization Check button

Error Details       Error when opening an RFC connection (LB: Hostname or service of the message ser

SMT2--Authorization Check button

Error Details       Error when opening an RFC connection (LB: Hostname or service of the message ser

Instead all the RFC destinations are successful and the default RFC destinations:

TRUSTING@<sid>_<inst. no.>

TRUSTING@<sid>_<inst. no.> are failing with below error

Logon    Connection Error

Error Details       Error when opening an RFC connection (LB: Hostname or service of the message ser

Error Details       ERROR: service '?' unknown

Error Details       LOCATION: SAP-Server xxxxxxxxxx_<sid>_<nr> on host xxxxxxxx (wp 1)

Error Details       DETAIL: NiErrSet

Error Details       COMPONENT: NI (network interface)

Error Details       COUNTER: 4

Error Details       MODULE:

Error Details       LINE:

Error Details       RETURN CODE: -3

Error Details       SUBRC: 0

Error Details       RELEASE: 720

Error Details       TIME: Fri Jan 03 19:38:59 2014

Error Details       VERSION: 40

Please suggest in solving the issue.

Best Regards,

Bharath S Bojedla