You've wired it back up incorrectly. Provided it's not a spur there should be three sets of wires in the back box. Most likely you mistook the outgoing wires to the lighting ring for the wires to the fitting. If you have no idea what I'm talking about call in an electrician - randomly attaching wires without understanding the principals of what you are doing may get you killed or cause a house fire!
Mr Big, January 2007
