97 Ignition switch gone bad for the 2nd time!

A couple of months ago the ignition switch went bad on my 97 XJ. I have had the Jeep for 14 years and that was the first time it went bad. It was fine and then poof! One day it just quit starting. I had no troubles leading up to that point. I went through a series of tests to figure it out and even cleaned the NSS. Finally I purchased a new switch from the dealer I work at. Well now the Jeep isn't starting again. It started giving me trouble about a week ago where it didn't want to start the first time I turned the key. Now it won't start at all. I tested the wires leading to the switch when I fixed it last time and they were completely fine. Why would a brand new Mopar switch go bad? Is there something that can cause them to fail?