01 silverado front diff wont lock

I;ve got a 01 Z71 when you push the button for 4hi, your can here it go but the diff wont lock. I've replaced the actuator on the diff and it still doesnt work. Help Me Please!!!!!!!!!!

-Shane

Fuses?
If ok you will need to get it on a vehicle capable scanner and attempt to get communcation with the pcm/vcm/and insturment cluster.
If so get the codes and post back codes.
MT

fuses are all good, Im going to try to hit it with a scanner today