1994 galant with overdrive/transmission issues

I bought this car with this problem, it will drive fine but will not go into overdrive. I have to drive with the od button off. As soon as I push the button it acts as if it shifts into neutral. Anyone with Ideas of what this may be? thanks, mike

Sounds like your o/d gear in the transmission blew.or it could just be a faulty o/d switch in your shifter.