Another gauge corrector--cheaper than MeterMatch, 33.00

I installed a Meter Match this afternoon. Hooked up all the wires. Began process by setting for full tank. Switched the selector to #1, turned the key and started bumping the needle to full mark. One it hit the full mark I hit the set button and then returned the selector wheel to zero.

Heres the problem, when I turned the key and started the car the needle rose to 3/4 mark then slowly returned to E.

Started getting hot in the shop so I quit for the day. Any ideas out there? Wish Tanks Inc would include a trouble shooting guide.