won't go in gear

I just rebuilt my 4 speed and got the car running today. I put it on jack stands to run through the gears and try it out. At first it was going through all the gears fine. Shifted smoothly. I put it on the ground to try all the gears with pressure on the drivetrain. Tried all the gears a couple times and they all worked. Then all of a sudden I can't get it to go into any gear. If by chance I can get it into reverse or 4th gear I can ease out on the clutch and it catches, push the pedal back in and it releases fine. Could the shifter be binding somehow? I put an allen wrench in the adjustment slot and it went through all the holes. :banghead: