question about amp wire (remote)

So i just installed a new head unit (JVC KD-HDR50). I had a (Sony Xplod CDXGT520). i noticed that the plug in for the sony fit inside the back of the JVC so i just used that plug in. Everything works great but im not getting power to my amp. I grabbed my voltmeter and checked the amp its got power to the 12v the ground is solid but there is no power going to the blue wire at the amp. IS there supposed to be or not. There are no fuses for the blue wire it runs from the head unit direct to the back and then to the amp. I checked all of the fuses amp has 2 those are good and the main fuse under hood is good and has power. What did i do wrong? did i need to use the wires that came with the JVC even though everything works great>
thanks for you help guys.

Just because the plug fit does NOT mean the wired pins are the same. You are lucky you didn't blow something up.

You need to find where the remote wire from the amp comes into the harmess and connect that wire to the blue/white wire on the headunit.

I did that. The wires from the sony are in the same exact spot as on the JVC wires that i did not use. I looked at the sony deck and matched that to the JVC deck. The wires all line up (same output as well) any ideas.

if you have a multimeter, check to see that the blue/white wite has 12V when the headunit is on. If you have wired it to the solid blue one, that is the auto antenna wire and will only have 12V when the radio is on.