Wiring a cooker hood

Please advise!
I have a new cooker hood which needs to be connected up to an existing switched connection unit (previously a fan attached). Problem: only a live (brown) and neutral (blue) from the hood to connect to three wires (live, neutral and switched live) - the cable coming from the switched connection unit. I tried connecting the two live wires and two neutrals (obviously turning the power off first), but it didn't work.
Worried that I need to get some more wiring/switch? Please help!

where does the fan switch get its power from?

Thanks for the reply. The Mains feeds into the switch connection unit, and the cable to where the fan was located (now hopefully the hood) I believe comes directly from this switch. My one concern is that because the cable comes from the direction of the ceiling and the switch is just above the work surface the cable may be coming via a junction box above the ceiling and not directly from the switch. This makes it more complicated if I need to change the wiring because I can't access the area above the ceiling very easily.
Is there any way of connecting the cable from the switch to the hood cable, considering the switch cable has a live, switch live, neutral and earth (forgot to mention earth previously, but largely irrelevant I guess)? The hood cable just has a neutral and live.
NB. The extractor fan that was in place was a UAX100HT with built in humidity sensor which switched the fan on if it reached a certain humidity.

The fan switch may well get tis supply from the lighting circuit. Bear in mind that your cooker hood will probably use more power than a "straight through the wall" type of fan. What is the power rating?

And to answer your question, forget switched live (providing you know for definite which this is - how do you know?) and connect live and neutral as normal, and earth. switched live should be terminated in a spare bit of terminal block.

Thanks for your help - I've managed to get it working!
It seems it was the lack of using a proper barrel connector that was the problem. Connected live on hood to switch live from switch in the end because I thought this would add extra security. Either live worked though.
Do you agree this is safer, or no difference?
Only slight worry I have is that the wall switch glows dimly even when the switch and hood are off. I assume this is because one of the lives is not connected (although safe in barrel connector) whereas when they were connected to the fan all wires were connected.
Thanks again.