tach and shift light problem

[bottomlesspit 2]

Just installed a sport comp tachometer w/ shift light from auto meter and am having some problems with it. First time i tested it, it worked great. But the next time i drove, the shift light wouldnt go off. On top of that, the shift set became limited from 3000 to 6000 rpm. Other than that the tach works fine. It still reads the proper rpm. I am wondering what is causing this, what can i do to fix it, and why did it only start the second time i drove.