At a guess, I would say ignition wiring. Connected wrong, as you have changed switch, try pulling them all off except from battery, mark them first if not sure what goes where, you need battery to switch, then you need wire to start solenoid, you will then need power to the start electrics, which should wire to a point marked ign or similar, use test meter if not marked, if standard switch, turn once, all except start wire should be on, in off position nothing on, turn to start, ign and start should be on, others off
SD, August 2011