Shifting problems 2001 Chevy Silverado

Hello all,

I am having trouble with my 2001 silverado shifting, 4L60-E transmission. If I put the truck in drive and try to go it wont shift out of 1st gear but if I start in 1st and manually shift it shifts with no problems. I have read elsewhere that it could possibly be the ignition switch, which I replaced with no luck. I am inclined to believe the problem being either the shift solenoids or the wiring harness. Any other opinions/ideas out there? Any and all help is appreciated. Thanks!