In my experience you (and I) bought the wrong resistors. Here's the more complete experience:

1) Ohms is backwards. You need a 3 Ohm resistor to flash two bulbs, not the 6 Ohm one. The 6 Ohm one only replaces one bulb, so it works on the backs but not the fronts.

2) You CAN buy special LED flashers, but keep in mind the ones you can find are limited to '35W', and they burst into flames if you use a LED flasher AND a resistor.

3) Make sure you use the TURN signal to test your flashers, since the hazard lights will often flash at the correct rate, even when the turn signals won't.

4) Bulbs get hot and will melt your cladding if you leave them dangling around. The resistors also can get hot. I recommend the models from VLEDS etc that are encased in their own heat sink, at the very least.