Sap R/3 and XI -- Commit fault ModuleException. Please help

Hi All,

I have a RFC interface between Sap R/3 and XI.

I am getting error in SM58 in R/3 :

Commit fault com.sap.aii.af.mp.module.ModuleException: call to messaging.

If I do test connection on in SM59 on TCP connection it's ok.

For the above error I also receive for some time the below SLD error message in RWB of XI

"Error during communication with System Landscape Directory: HTTP response code: 503 (Not Ready)"

Please advice as it is production problem.

Regards