Trouble with lightbox JS 2

I have tried 2 different plugins for lightbox 2 on my blog and neither of them work. I have tried:

https://zeo.unic.net.my/notes/lightbox-js-version-20/

and

https://www.4mj.it/lightbox-js-v20-wordpress/

Once the plugins are installed I can see that the extra scripts are included in the code when I do view source, but the images only ever open in the main window like a regular link, as opposed to the lightbox popup effect.

I have added rel=”lightbox” to the link.

I am using the blix theme.

Is there anything else I can do to troubleshoot the problem?

Thanks