Cold Radiator and towel rail

[tigersb]

I have a caravan with a brand new heating system.The Valliant combi boiler is working fine but one radiator and one towel rail are stone cold.I have bled both and also tried to balance the radiators with no success.Even when I shut off all other radiators the problematic ones still don't heat up.Any help would be appreciated

 

[exedon2]

New system? non working rads?Just get installer back.