Everythings ok except right rear speaker

[awpi]

I have a 94 chevrolet cavalier station/wagon. Recently changed the factory radio with Sony Xplod. I use wiring harness and i am 100% sure connected every wire correct (maybe 99%) .

Here is the wiring diagram that i used :

Left Front Spkr (-) White w/ Black Stripe

Left Front Spkr (+) White
Right Front Spkr (-) Gray w/ Black Stripe
Right Front Spkr (+) Gray
Ground Wire Black Black
+12 Volt Ignition Wire Red
+12 Volt Battery Wire Yellow
Right Rear Spkr (-) Purple w/ Black Stripe
Right Rear Spkr (+) Purple
Left Rear Spkr (-) Green w/ Black Stripe
Left Rear Spkr (+) Green





On wiring harness i have Black (Ground Wire), Orange (Headlight Dimmer Wire), Blue (Power Antenna) wires i taped individually.

Everything is working except right rear speaker and also i'm getting failure message on my sony deck when i turn it on (which means "the connection of speakers is incorrect).

My questions are ;

1) Do i have to connect to black wire from wiring harness and other black wire from deck together ? (I connected the black ground lead (from deck) to a metal surface of the car)

2) Does my car has an external amplifier ? If yes should i use blue power antenna wire from deck? How ?

I'd like to know my alternatives.

PS: The all speakers were working with my old radio.

Thank you for your time.