No Sound when I turn my car over

I have a situation where when I turn my key and my stereo boots up and I can hear it. I then turn the key over and start the car and now I have no sound. Stereo is on, amp is on but I get no sound. I turn my key back to just have aux. power and then I have sound. Someone please help!

you have the switched power lead from the headunit connected to the wrong source

Please walk me through this. Let me tell you what I did first. I wanted to add a sub to my system so I went under the hood an disconnected the inline fuse that I had my system connected to. I then went back and disconnected my current amp as I was putting in a 2 way amp block so I could hook up my sub amp. I took off my dash and pulled out my sub RCA cables and attached a 20ft RCA chord and then ran it under my carpet and up my step plates where my current chords run. From there I ran all of my new wires for my mono amp and screwed it down in place. I do not have any power running to it yet as I am waiting on my sub box. I took the power chord and reattached it to my current amp and the re connected the inline fuse under the hood.
I know turn my car one click to aux power and my radio will boot up as I have a Pioneer Avix series and I will then hear sound. If I turn my key over to turn on the car I have no sound but power to everything. Where the hell did I go wrong? I thought I did everything right. Please walk me through this.......

Now I am getting sound when I turn my car over. I listened to it for a few minutes and then it fizzled out. Came back on later. My amp is now getting 13.3-4 in voltage and it use to get 14.4 on the button. What is wrong?

If you turn on the headunit and all the amps come on but the headunit dies, then the problem is somewhere in the headunit or how you have it wired. The fact that it will play in some key position means the system itself is fine. I think the red wire from the headunit is attached to a power source that is not switched when the ignition is on.