communication error for distributing module view in idoc.

Dear,

I have configured the distribution model of IDOC in bd64. when I distribute it to destination logic system. it gives me error'

Communication error occurred

Error when opening an RFC connection (CPIC-CALL: 'ThSAPOCMINIT' : cmRc=27 thRc=2

'

distribution model:

what could be the reason cause the error? if you need further details, I could provide them. thanks!

Best Regards

T.P