Confused.... installing new HU in my car and can't get it to power up

Just bought a Dual XDM6400 and tried wiring it up. My car was broken into and the wires were kinda messy. Dude at the store said to hard-wire it so I didn't get any harnesses. Looking at the wiring info in the deck manual, it says the yellow wire is "memory" and to connect to constant 12v source, the red is "accessory" and to connect to an existing ignition circuit or switched 12v source, and of course black is ground. Looking at my repair manual for my 1978 Buick Electra, it says orange is the constant 12v and yellow is the switched 12v. So I connected it like this:
Deck ==> Car
Yellow ==> Orange
Red ==> Yellow
Black ==> Black

I have yet to connect any of the other wires (remote turn-on and the speaker/pre-amp wires). Initially, the only loose black wire I saw had a ringed connector at the end of it, so I snipped that off and wired everything up. Turned the car over and no response from the deck. Tried another black/ground wire off of a disconnected harness of some sort and still no response from the deck. I'm at a loss, is there something I am missing? Shouldn't it power on at this point? What should I do?

 

I actually just finished doing both of those things. The fuse in the radio spot on the fuse block is 20a but its supposed to be 10a. Checked out the length of the wire and it appears to be in good shape, no melting or anything so I'll replace the fuse ASAP. The orange wire coming out of the car is definitely hot at all times, but the yellow one is not hot... ever. Not in off, acc, or run. There were an assortment of other wires hanging out back there, tested them all and none seemed to fit the cold in the off position, hot in acc and run category. Confused again. Where to go from here? Thanks for the response.

 

Ugh, I feel like the world's biggest idiot. I went and got a 10a fuse and pulled the 20a out and noticed that it had the tiniest break in the circuit. It was like a hairline crack, no black/brown spots or anything. Replaced it with the 10a and everything went swimmingly. Thanks for the help!