Strange problem in my harness

I'm trying to get up to speed on the master/participant model in croquet and have run into a few problems with process interactions and was wondering if anyone can suggest what might be going on.

I have a method where my AvatarUser is entering a new space and it calls a TTeleportUtilities method makePortalToAnotherWorld.

In that method, it tries to connect to a postcard using the following snippet:

    harness := Processor activeIsland project ownerMorph harness.

It quite often comes back with nil. When I step into the code occasionally there's my harness, and occasionally it's not.

Any pointers on where I can find out how this stuff is supposed to be wired together?

Thanks,
Steve