Lightbox on Portfolio Gallery, not individual pages

Hey there,

I have installed this awesome plugin, as I want to be able to enable this on portfolio items instead of them linking into the single portfolio page.

I’m finding difficulty editing the php so that the portfolio thumbnail images links to itself and not the page. Can you please help?

I have tried this code which I found on the single portfolio page:
ID, ‘gt_project_url’, true) ?>”>
(The lightbox works perfect on the internal pages).

Thank you heaps!

https://wordpress.org/plugins/responsive-lightbox/