When i was re fitting my gauges into my new dash, i had to connect my temp, oil pressure and volts. all of them work fine, but when it came to reconnecting the volt gauge, the light seems to be the problem. when the engine is off, and i turn the parkers on, the lights on the gauges appear on all , however, when i turn the ignition, the light in the volt gauge turns off!

. And this also occurs the other way as well. for example; when i turn the parkers off with the ignition on, the volt light comes on and the rest turn off. Basically it has opposite effects with the other lights.
This may seem very confusing so thanks for ya paitence.
and the wire for the light on the volt guage is the same for the oil pressure and temp guage lights. So i dont understand why its doing this to me?
please help greatly needed.
thanks fellas