Recheck the bulb is fitted correctly. If you have some 800 grade emery paper clean the bulb holder. Check that teh bulb holder central contact is actually touching the bulb. I seem to remmeber buying a bulb that was 2mm shorter, and having to bend the centrl contact slightly to get a good contact. Check the earth wire is also got a good cleam contact and hopefully it will work. I had a bulb warning for a while then a bulb blew. AFter another new bulb it was OK.. Bulbs are not as good quality as they once were. I have had other bulbs too fat for the bulb holder! I hope you sort it. Check the front side lights are good clean contacts too.