My Vulcan continental 45/60 pilot light clicks off after every cycle?

At the moment we are having to relight the pilot light manualy every time it is due to come on !!! The boiler goes through it's timing cycle fine and heats the radiators and water as per usual but then about 30 seconds after it stops there is a clicking noise and the pilot light goes out. I have changed the thermocouple and put a universal one in. Can anyone advise what the problem may be please.