Why doesn't my speedometer work on my 2000 GMC 1500?

What is your question?

My speedometer stopped working so I bought a speedometer cluster from my local GMC dealership and installed it myself. All gauges work except for my speedometer? I then changed my speed sensor and ran the truck down the street and the speedometer still doesn't work? What else could be the problem?

What makes this problem better or worse?

Nothing makes it worse or better, just doesn't work.

How long has your 2000 GMC Sierra 1500 had this problem?

Gave truck to son, hasn't been working for at least a year.