I had to turn on the logging in my metadapter, the relevant bits:

12-Nov-12 08:25:17,128|ERROR|LightstreamerLogger.pump.messag es|SERVER POOLED THREAD 4 |Error in message forwarding for XXXX_UNICAST: Wrong message received
12-Nov-12 08:25:17,128|ERROR|LightstreamerLogger.connections |SERVER POOLED THREAD 4 |Failure in request processing: Error in message forwarding: com.lightstreamer.interfaces.metadata.Notification Exception: Wrong message received