My guess is that you may have a bad guage and not a bad switch or you got the wrong switch to begin with. If you still have the old switches try putting them back in and see if anything changes.
Did you use any sealant on the treads of the switch? If you did maybe it isnt getting grounded correctly?
Did you use any sealant on the treads of the switch? If you did maybe it isnt getting grounded correctly?