7W is on the low side of the range it should be able to handle, might be too near the edge, in that case a bypass may help. But before you go that way:
Are you sure the led bulb is dimmable? Are yo able to dim it at all and is the range for dimming just really narrow, or is the bulb only on or off, nothing in between?
The dimmer does not really say much in the manual about the dimming technology. Some led bulbs are designed to exclusively work with leading edge dimming, others trailing edge. Might just be the led light is dimmable but not compatible with the dimmer technology.