66 C4 won't go into gear???

We finally got the my motor rebuilt and back in the car. While the engine was out we also replaced the neutral safety switch and transmission filter. Now the transmission won't go into any gear when the shifter is moved. Although changing the neutral safety switch wasn't as easy as everyone here said it would be, I was finally able to get the small drill all the way in by adjusting the shifter. I think it's correct now since it will only crank in park or neutral but why won't it go in any gear? I understand that the C4 holds 4-5 qts of ATF but isn't that torque converter and all? If all we did was drop the pan we probably only drained about a qt., right? What am I doing wrong? Thanks in advance for your help.

We only added less than a quart to show get the dipstick reading were it should. I know your supposed to check the dipstick after the car has been driven, but like i said, it won't go into any gear. Any idea why???