Transmission won't go in reverse.

I rebuilt my 727 trans last year and put in a trans go shift kit in it. I bought a 440 from a motor home with trans I switched the tail housing when I had it all apart. I also put a sidewinder shifter in it. So now I got the car all assembled and ready for a test ride. It moved forward about 4 feet then I tried reverse and nothing. Any ideas of what to look for?


Thanks

Sid