I am not an electrician but I think the brake light switch should have power in on one side, power out the other to the bulb, which then earths through the bulb holder? Your diagram shows the switch earthing directly back to the resistor. I think the green wire from the bulb should go to the switch side that is currently earthed, not to the connector giving you two greens at the switch........... but as I say I am no expert and if the bulb holder is not earthed then I have just talked rubbish, so someone else may be along soon with better advice.