2004 Silverado Radio Power Problems

I recently installed a Alpine IDA-X001 into my Silverado but I have one problem. I noticed that there is 2 orange power cables coming from my vehicle. 1 I hooked up as the main battery lead and the other to the switched igniton lead. I can not get the Alpine unit to turn on. I tested the 2 orange cables for voltage with the igniton on and I am getting 12 volts from one but 0 from the other. Any advice as where I should start? Thanks

I tested both power leads today and found that the ignition switch wire is not giving off any voltage at all. Even when the ignition is on and the car is running. Is there a fuse for this wire any where?