Did you import correct transports correctly? Which transport did you import. What's your R/3 version? What's the patch level for SAP_BASIS?
To investigate you may check SM37 and select all the cancelled jobs by the R/3 user you are using for the connectivity. If you find the cancelled job, you should see some helpful information in the job log. Also check system dumps and system logs (SM21) on the app server you are connecting to.
Please post your findings so I can be little more helpful.