wiring in reverse light flasher

Ok i tried it before i had it to where it wig waged both reverse lights like they were supposed to but when i put the car in reverse only one light would work. The company emailed me instructions but they are confusing and i cant make any sense of them. Could someone do me a writeup?

Wires are as follows.
White-Power
Black-Ground
Blue-Lamp output
Green- Lamp output
Brown- Lamp input
Yellow-Lamp input

I will do a quick pic of the wiring of the of the reverse lights.


These are the instructions i were sent via email when i had trouble.

"To connect the wigwag to the backup lights in your Impala you would cut the wire going to each backup light bulb (should be light green on your Impala). Connect the wigwag's blue and green wires to the backup light wires on the side closest to the bulbs (only connect the blue to one side and the green to the other side). Connect the wigwag's brown and yellow wires to the backup light wires on the side closest to the vehicle's harness."

Thanks for any help.

ok thanks for the help