Just a thought but do you have your batteries in the yellow battery holder and is your wall transformer rated at 9 volts dc at 1000 mil (1 amp) or higher. New batteries if not you may have a shorted battery.
I have found that if you have one of those chargers that the tips change so you can charge different thing, the tip might need turned around. You can try this if this does not work than you have a bad charger.