Boiler problem

I have a potterton suprima 40 that will not run the radiators.
Turned the radiators on for the first time last night for ages and nothing. The water heating is working ok, so no problems with the pilot light or the ignition. I\\\'ve turned the wall thermo to full and have tried all possible permatations on the selector but cannot get the radiators to work. Any suggestions before I get the experts in ?

Probably a faulty motorized valve. You'll have either one with 3 pipes or two with 2. Each type usually has a lever on the end you can move to a latched "manual" position. Put the HWon and the rads should get warm, to diagnose . That usually means a new "head" on the valve, or you can often change the motor within. Could also be the programmer , thermostat etc of course.

I had similar problem caused by Honeywell motorized valve sticking.
I removed motor from valve, operated valve by hand a few times, introduced a squirt of WD40 problem solved.