Three bulbs were purchased to work together above a kitchen island, but they will not work as a set. According to the information provided with the bulbs, the total wattage, of the set, should be between 1/5 of the maximum rating of the dimmer switch and 1/6 of its minimum. The dimmer switch is rated 40-210 Watts therefore the bulb set should be between 6.6 Watts and 42 Watts. These three bulbs together are 33 Watts, so should work ok. But they will not light. Any two bulbs work fine, so bulbs and fittings are ok.
Further investigation suggests a different calculation, not in accordance with Megaman recommendations. Each flourescent reduces the capacity of the dimmer by half. That is; 220w to 110w for the first, 110 to 55W for the second, and 55 to 27.5W for the third. Therfore three at 11w won't work. A different dimmer may work, and may cost £25 but will not match the others in the set.