What does the SystemOut.log say? What are you doing to get "unable to connect to data source?" Are there exceptions relating to DB2 in the SystemOut.log? Can you telnet to the DB2 server over 50000?
The forum entry http://www-10.lotus.com/ldd/stforum.nsf/DateAllFlatweb/90eb8d14675c3a9185257793004d9ac0?OpenDocument
suggests that he resolved the problem by federating the primary node with the deployment manager but that is only required when deploying a cluster which requires a deployment manager to manage the cluster members. Can you email me the steps you have taken so far? firstname.lastname@example.org