95 Jetta Gas Gauge Problem

I have recently been given a 1995 Jetta III GLX and too my surprise I found that the gas gauge does not registered. I have looked at other forum posts and seen that it is probably a problem with the fuel level sender unit. I found it in the trunk and used a wire to connect the two small wires together but nothing happened. What is the next step I should take, and what are the most likely problems?

If you have the tank off i would pull out the part that reads the fual and then put a multimeter to it reading the resistance. Then as you move the lever on the fuel level sending unit the resistance should change.