Hello Uday,
Please go to transaction SOST.
There you will see the Failed entries of those messages.( or in waiting state)
If they are in failed state please click on that message --> Send Request (from menu bar) --> Display Trace.
By this you will get an exact error why this messages are not flowing.
If its yellow, then please go to transaction scot and check your sapconnect is correctly configured.
Thanks.
Parimal.