O2 sensor & a/f gauge question

[quicknismo]

I am having a problem with my a/f ratio gauge. First off, there are three wires coming out of the 02 sensor, brown (12 volt feed) , brown/yellow and white. When I connect the gauge wire (purple) to the white wire, nothing happens and when i connect it to the brown/Yellow wire, the light stays in the green (rich) area and dosen't move. Is this the idication of a bad O2 sensor or is it more of a wiring issue.

This is a s13 Blacktop in a 90 fastback :)