help installing Drayton LP711?

I installed this yesterday. Had to change the back plate so wired the new one as per the diagram.
Blue - neutral
Red - red
Yellow - 1
Yellow&Green - earth

There's power to the unit and I can set the timings, etc, but it doesn't turn the heating on!!!!

I have 3 wires plus an earth, should I have wires to connect to 2, 3 & 4

Help, I'd really like to do this myself without having to call a lecky.

Thanks