It looks like you have the wrong switch; the one you took off is a 2 terminal switch (1 gang) but you're connecting up a 3 terminal switch (2 gang). Find out more here:
https://www.diydoctor.org.uk/projects/wh ... switch.htm
It's hard to see but that's what it looks like. If this is what you are trying to do (ie, add a 2 gang switch), it might be a a good idea to get an electrician in. You can find a local one here:
https://www.diydoctor.org.uk/find-tradesmen/
