Nav installed but the reroute isn't working?

[MDC9966]

I put an OEM nav unit in my 07 tahoe from a 2010 truck. The nav unit map displays and the symbol for the vehicle moves on the map as I move. But it doesn't reroute and the turn/turn directions doesn't work. I located the VSS wire and tapped into it with a crimp lock but I'm wondering if it maybe isn't making contact. Does this sound like a VSS signal issue to anyone?
thanks

 

[MDC9966]

So for anyone else that has this issue, I respliced my vss wire and made sure it was connected to the head unit. Now it all works as it should. The unit reroutes, and it gives turn by turn instructions.
Hope this helps someone else.