Less well explained I think - you fail to mention that the lamps are low energy types...
Low energy lamps typically do not work with dimmer switches. Some manufacturers make low energy dimmable lamps but they are V expensive (£18.49 inc postage = 500 year pay-back).
Fit regular lamps in your light fitting and see what happens?
http://www.reallifenews.com/environment/2007/02/low_energy_light_bulbs_for_dim.php
Peccavi
October 2008