According to Lutron Electronics, not all LED lights can be dimmed. The packaging must be labeled as "dimmable" and an LED-specific dimmer switch must be used.
LED lights do not function in the same manner as incandescent bulbs. Even with the proper LED light and dimmer, it may be impossible to dim the lights as much as with incandescent bulbs. If the dimmer switch is set too low, the light will not come on at all, warns Lutron Electronics. Fluctuating voltages within the home may cause occasional flickering. On the favorable side, LED lights do not change color as they dim and can help save on electrical costs.