92' Sierra 4 wheel drive problems

I have a 92' 1500 4wheel drive.The front drive shaft is receiving power when locked in 4 low or high, but not getting to the tires.I have replaced the actuator and upgraded the wiring harness that came with it.Any suggestions?

Are you getting power to it? You should hear it engage.

Have you attemped to engage it while moving or did you try to get it in 4x4 sitting still? It might not work if you don't move the truck for the plunger to mesh. I know this sounds like a stupid question but someone I know (no not me) did this. He replaced the actuator, the wire harness and ran the new brown (? color) to the shifter but it would not engage. He spent some time going back over his work and could not figure out why. Thats about the time I was driving by and seen him fooling with his truck. So he ask's me to sit in the truck and try the shifter while he jiggles some wires below. After about 5-10 min it dawns on me he has to move the truck to get it to engage, so I ask if he did that, NO. I started truck and moved a few feet and bingo, it worked. He had been fooling around for a couple of hours and never started the truck or tried to move it. Sometimes its the simplest things.