ClassNotFoundException trown when registering Midlet in the PushRegistry

Question

I'm getting an odd error I can't get to the bottom of. When I register the midlet in the Push Registry it throws the ClassNotFoundException. I've used a very standard implementation straight from the API documentation just the url has been altered

//  MIDlet class name
String midletClassName = this.getClass().getName();
//  Register a static connection.
String url = "sms://:2049";
//  Use an unrestricted filter.
String filter = "*";
PushRegistry.registerConnection(url, midletClassName, filter);

this for some reason throws the java.lang.ClassNotFoundException! When I view the JAD it looks ok:

MIDlet-1: AlarmHandler, ,sweoch.test.AlarmHandler

which is the class midletClassName equals at debug. So why is this trowing exceptions?