I had a failed HR92. I replaced it using DMandrake's formula of changing the zone type to zone valve to remove binding to the previous HR92, changing the zone back to radiator and then binding the new HR92. This appears to have been successful: the HR92 declares that it is bound to the correct zone and appears to be following the schedule. But, on the controller the zone does not display a temperature just the egg timer.

I have cleared the fault log and left it alone for a long time (24 hours). What have I done wrong and what should I do about it?