Cluster works, but one computer never utilized

I've got 4 computers that I'm clustering, all with the latest Compressor (4.0.7) and the same OS (10.7.5). I'm able to create a cluster of managed services and also a quick cluster that will utilize unmanaged services, but one machine will never be used in the cluster. I've tried restarting all of the machines, creating different clusters, removing machines from the clusters with no luck. The machine in question will show up in Qadministrator and I can add it's services to a cluster, but during a compression, it's services will all remain idle while all other clustered machines will work away.

Any ideas?