It should work as-is, your ground wires to 87a appear pretty small but it doesn't show to well... do the relays click when you operate the switches? The way it should work it each motor lead should have continuity to ground as long as the relay isn't energized... when power is applied through pin 86 it closes the relay which removes the path to ground on that relay & connects pin 30 to the output (pin 87) so now you should have your power through the energized relay & your ground through the unenergized relay.. Power flow wise pin 30 & pin 87 are interchangable, the reason to hook the motor lead rather then the power lead to pin 30 is with no power energizing the relay 30 & 87a have continuity so 87a can provide a ground path...