Need help with aftermarket tach

I have a 98 2.5l with the idiot cluster, so I got an aftermarket tach. Tach has positive, neutral and illumination connection, and the tach is wired to the negative wire on the coil. Backlight does light up, but needle does not move at all. What am I doing wrong here?

Sounds easier to get a full gauge cluster and just swap it in and gain all the gauges at the same time

I actually figured it out, bad connection on the positive wire. I might get a full cluster in the future, but the tach was free, instead of $50-100 for the full cluster, although it would be nice to have a temp and oil pressure gauge also