on my 2008 Silverado I replaced the lock switch on my driver side because it wasn't working. now it will unlock the doors but no lock. where to look now?

 

Lubricate the contact points in the door and the new lock plastic parts in the door handle. Does the doors lock with the key and not the button? If not, lubricate inside the keyhole as well. (Wouldn't hurt to do that anyhow)