LED's run on very low output so you want to be sure you are using a dimmer switch designed for LED lighting. If you have a dimmer switch for an existing incandescent light, output to the light will reduce as you slide the dimmer. This could cause the light to blink or not come on at all due to lack of power to the light. Older dimmer switches are designed to control an incandescent bulb that runs on a much higher output than an LED.