jaguar boiler, heating but no hot water

[viperuk1983]

Hi i have a jaguars boiler, which has been working fine, until today, the heating works fine and it ignites etc when it needs to, but when a hot tap is run nothing happens, it doesnt ignite and there led on the tap icon, is still on heating and not the tap icon as it should be?

does any one know what could be causing this fault, theres no errors on showing on the boiler

thanks in advance