Session replication problem!!

I have set up a cluster with two WLS 8.1 servers (on the same machine runnign on
different ports) managed by admin server that hosts the httpclusterservlet. When
i access a simple test page (jsp) that does a setAttribute of a string value i
see the following messages on the console. It is evident that replication is not
working
<br><br>

<Creating primary -1838345955235954809>
<### becoming primary for roid = -1838345955235954809>
<**Secondary candidate list>
<Unable to create secondary for -1838345955235954809>
<#### Returning getSecondaryJVMID()=NONE URL=null>
<Sending senderNum:0 seqNum:73 message:Heartbeat with 2 items>
<#### updating with secondary=null>
<Unable to create secondary for -1838345955235954809>

Has anyone come accross this problem before and resolved it?
Please Help!!

I see messages of the JVM ID sent by both the managed servers.  I haven't
configured replication groups. I have assigned machine names to both the servers
and have set the persistencestoretype to replicated in weblogic.xml.

But still have the problem of "unable to create Secondary"

When i query the ClusterRuntime MBean using weblogic.Admin as suggested by the
support patterns i do not see the names of all the servers however the admin
console shows both servers to be active and runnig on the cluster.

Can anyone please help!!