4 Wheel Drive/SUVs: 91 Chevy 4x4 front hubs will not engage, ill family member, chevy pickups

Question
Hi Adam.  Front drive shaft is turning.  Replaced actuator.  Still not engaging.  What am I missing>?  You help would be greatly appreciated.

Answer
Eldon sorry for the delay I have had an ill family member so I wasnt able to get back to you right away on alot of the chevy pickups, on top of the transfercase there is a switch that sometimes goes bad, and it isnt very expensive check and see if your truck has one of these thanks ADAM