Couple of days ago my 2006 Saturn Ion transmission stopped working. I can put the car into drive but when I hit the gas it just revs up and doesn't actually go anywhere - it will roll though like it's in neutral when it's in drive.

That being said when I put it in reverse it works just fine, which leads me to believe it's not a transmission issue. I haven't taken it to a mechanic yet because it was suggested to me that this could be a electrical issue so when I put it in drive, it's not communicating with the transmission to be in drive.

I did speak to a mechanic on the phone and he said that because reverse will work but drive won't, leads him to believe it's not the transmission at all, but he's not 100% sure.

What do you think, could it be the transmission, an electrical issue or something else?