glow plug light

[worstmate]

I have a peugeot partner van 1.9d on starting in the morning the heater plugs dont work (no light either).

Once I mange to start it i can turn it off and then the light comes on and the plugs work. I have fitted new plugs and the heater plug relay on the o/s inner wing. I have also fitted a new temp switch (the green one on top of the engine as the blue one seems to operate the temp guage) just in case the heater plugs are linked to engine temp.

I would be grateful for any ideas.

???