Why does 1999 Mitsubishi eclipse speedometer not register speed?

I have a 96 that does this. Still tring to figure it out. I just went to a garage and spent

203.00 dollars on a part and labor this part was the speed senser and this did not fix it. im out of money this week, so ill come back and let you know what it was.

idk if I'm late here but i had the same problem i am an automotive technician and the problem is that there is a gear inside the transmission on the trans axle that's plastic and it falls off or breaks off one easy way to test this is to take the speed sensor out and then remove the gear from the top of the transmission and take a drill and spin it and see if your speedometer registers. if it does then the problem is the gear inside the transmission. I've changed mine and then it worked!