Resolution:
When deploying a Domain to Engines, you may get a null pointer exception on Engines similar to the following:

08/07/06 16:53:02.516 Severe: [DomainManagerPlugin] while activating: WL81SP5IOAppDomain
java.lang.NullPointerException
        at com.datasynapse.fabric.engine.plugins.DomainManagerPlugin.activate(DomainManagerPlugin.java:98)
        at com.datasynapse.fabric.engine.plugins.DomainManagerPlugin.access$700(DomainManagerPlugin.java:53)
        at com.datasynapse.fabric.engine.plugins.DomainManagerPlugin$ICActivate.run(DomainManagerPlugin.java:405)
        at com.datasynapse.fabric.engine.plugins.DomainManagerPlugin$ICActivationQueueHandler.doRun(DomainManagerPlugin.java:424)
        at com.datasynapse.fabric.util.StoppableRunnable.run(StoppableRunnable.java:21)
        at com.livecluster.util.threadpool.ReusableThreadPool$InternalThread.run(ReusableThreadPool.java:335)

This exception occurs when you deploy a Domain that depends on a Container that is not installed, usually when a Domain has been copied from another Broker. For example, if you install WebLogic on a test Broker and create a Domain, then copy that Domain to another Broker that does not have the WebLogic Container installed, the above exception will occur.

To correct this issue, install the missing Container on your Broker, or use the Domain Wizard to create another Domain that uses a different Container.

DomainManagerPlugin Exception When Deploying a Domain