When I hit the 4x4 low switch it does not go into 4 low, but the light flashes. What could that be?

Create a sig line so we will know what kind of truck you have. If it is a newer truck, you will have to stop, put it in neutral then move it into 4low. Repeat to get out.

Yeah, thanks for the heads up. I did do all of that but still won't click in.