Car won't start with key

[g81981]

I tried to start my car with my key and it wouldn't start. The starter doesn't seem to do anything when the key is turned on. The car just makes a click sound when I'm trying to start the car. I tested the starter with a power source, it still works. I did a push start and the car starts and runs. I'm assuming that it's a wire harness problem. I thoroughly checked the wire harness for any open lines/bad wiring and it seems fine. What's wiered is that when I take out the key, the instrument cluster stays on as if the key is in the on position. I checked the fuses in driver's side footpanel and engine bay and did not find any blown. What's puzzling is that when I place the fuse tester on the reverse lamp fuse in the driver's side panel, the instrument cluster turns off. Any ideas to what this problem may be?