I have a system installed in 1999 that has pcms and a two year old bcu that I believe is a bmtx model. Occasionally when the bcu puts the air handlers into an unoccupied mode via schedule the pcms do not receive the control. This also has happened when the heating system shuts down and the vavs go to a reheat lockout mode. Has anyone seen this happen before? Is this due to the difference in generations of controllers that "should" work together? If I pull up the edit screen for a pcm it usually solves the problem after a couple of minutes. Cycling the power of the bcu does not solve the problem.