Three cables going into a light fitting: One will be a live feed, one will be the switch and the other will be the feed to the next light fitting, (the one that doesn't work at the moment.)
The cable you have connected already is the live feed to that light fitting. Find some way of identifying the other two.
All the red wires should be connected into the centre block.
The black wire which makes the light work at the moment should be connected into the neutral connector block along with the feed to the next light.
Having found the cable to the switch find some red sleeving or red tape and mark the black cable as live and connect it into the block on the other side of the light fitting. It should be on its own!
If this doesn't make sense then your best bet is to find someone to do it for you.
Hope this helps
Rich
November 2007