Then I found this in a wiki somewhere.
.Once HouseLinc 2 is done synchronizing with your network, you will want to prompt HouseLinc 2 to synchronize with your battery-operated INSTEON devices, which may each be displayed on your devices list as an "Unknown Device". As a battery-saving feature, battery-operated INSTEON devices "go to sleep," so all you need to do is activate them one at a time. For RemoteLinc (#2440, 2440BK), tap one of its buttons. For Motion Sensor (#2420M), activate it by walking in front it or tapping its Set button
I'm posting it here in an effort to help others with the same issue.