Hi
Iam not an expert on the dinalight dimmer, but the one's I have seen are only suitable for one way switching. The four connection are neutral in (blue wire from mains) Live in (Brown wire from mains) neutral out (blue wire to light) & live out (brown wire to light).
The three wires in your switch are for two way switching (switch wire & strappers), if you take off the switch or dimmer at the other end you will find that it has an additional two wires connected to L1 and L2.
I don't think your dimmer is suitable.
You could proberbly use the dimmer if you made the circuit one way switching from the end with the five wires, but you would only be able to switch it form one position.
Hope this helps
Clive