Does solder heat bother a resistor?

I am installing a trackside signal that shows red or green light. I tested it before attempting to install and with it all hooked up it now does not light. There are two light wires that go to the switch and a third with a resistor inline. I soldered additional wire to the wire with the resistor so I could attach it to my lighting junction block. I soldered the wires for the red and green lights to their respective leads on the switch. I tested the switch for continuity as well as seeing that it had 12V at the switch center lead and at the lead where the switch was set. I've run out of things to test.
While I had 12V at the leads going into the red and green lights, I'm not sure exactly how to test the lead with the resistor. It is not an insulated wire except for the wire I soldered to it. I checked all soldered joints for continuity.
Thanks for any help on this.

 

Heat does not usually harm a resistor, perhaps you have a cold solder joint somewhere.

 

Do you have 12 v across the wires as close to the lites as possible?

 

I have 12V where the light wires are soldered to the switch output. The resistor is on the other leg.

 

did you try revering the polarity of the 12 volts to the lights. You did not say if these are LED's or incandescent.

 

They are LEDs. Are LEDs specific as to polarity.

 

Thank you!! That was it. I reversed the polarity and got light.