Recessed Shower Valve No Flow

[2003cjh]

I've just fitted the recessed dual shower valve photographed. Flow was fine until I went to calibrate the temperature this morning, so twisted the bottom cartridge and adjusted the flow on the isolator valves. now there is no flow out of the head at all (isolation valves fully open) having put everything back as it was and I can't work out why. Any advice why would be much appreciated.
Thanks
Chris

 

[ShaunCorbs]

Need to leave the iso valve fully open and move the cartridge back to where it was not for regulating just move the temp nob over a notch/spline to adjust

 

[2003cjh]

Thanks Shaun. I have rotated the spline through to both full clockwise and anti-clockwise extents with the isolation fully open and no flow from the head

 

[DripsnDropsBognor]

Crap in the pipes? Air lock? Have you got a low pressure system or a combi boiler?
I have found a few of these recessed shower valves have very small waterways on the mixing valve and can be blocked by little bits of grit like hard limescale. Only happened on low pressure systems. Stuck a foot pump in the hole and blew it a few times live. Got very wet but cleared blockage