Coldfusion 9 clustering not working, internal server error

This is my first attempt at clustering CF instances and so far has not worked for me. The server is Windows Server Standard Serviec Pack2, IIS 7, Coldfusion 9.0.2 Enterprise Edition, multi server installation.

I created 2 CF instances, cluster1 & cluster2. In the main cfusion instance I created the cluster named testCluster, included cluster1 & cluster2, Round Robin, Sticky Sessions checked, Replicate Sessions checked. Cluster1,2 instances are running as well as main cfusion instance. I created an IIS website, ran the webconfig tool and connected the IIS website to the cfusion cluster JRun Server using IIS (checked to configure web server for CF 9 apps). Restarted all CF & IIS services. The cluster manager shows the 2 CF instances being included.

Trying to hit thetest website gives me an Internal Server Error: Module IsapiModule, Notification ExecuteRequestHandler, Handler AboMapperCustom-80599, Error Code 0x800703e6

in IIS the connector is pointing to the correct JRun4/lib/wsconfig directory that was created by webconfig tool.

Any ideas on where to look are appreciated

Joe