Replacement 2D lamps don't work?

Our bathroom light is one of these 2D lamps (www.geconsumerproducts.com/.../images/60055.jpg). It went last week, so I bought and fitted a replacement, but it didn't work. I looked for a fuse for the light and switch, but couldn't find one. The light switch also powers on the extractor fan which is still working. The main fuses in the fuse box are all ok. The starter works with th ekitchen light so it's not that. I guessed that maybe the replacement lamp was broken, so I bought another, but that doesn't work either. Now I'm stuck. Anyone know what the solution might be?