Switchback/ Led turn signal problems?

[Javier97]

I just recently bought a pair of switch back. When i went to install them i unplugged one bulb n put the switch back in check to see if i would light it did light n did flash amber. But the problem is when i went to plug up the 2nd one the white leds shut off but they would still flash amber. What could cause this?

 

[Frankp]

Did you put in resistors along with the LEDs? That is needed to make them work correctly.