help! no power to radio!
 

okay so i have a 1989 chevy blazer k5. it has the 5.7 l tbi engine. it is not the s10 version it is the full size. so the problem is that i hooked up the wiring harness to what i think are the correct wires to the wiring diagram. after i tried hooking up the stereo to the wiring harness i had gotten no power. right now im pretty sure i only have the constant connected to the harness but still no power. the new stereo is a xo vision xd107. when i got the the truck it had no stereo so im not very familar with what the other guy had done to it. he said there was an aftermarket stereo in it before but he had takin it out. i checked the fuse to the radio from the fuse box and it seems fine so i dont know what to do next. please help

check the ground wire, fuse and maybe run a direct power wire to the battery with an inkine fuse if needed