A couple of things to check.
1. There are 3 wires going to the signal lights. Make sure that the resistor is across the correct two.
2. If you have an ohm meter, check the resistor to confirm that it is still functional. If not, then replace it.
3. What value of resistor are you using? I'd have to double check but I think mine are 12v 25W 10ohm resistors.