Hi @aaronocampo, I just had a look at your site, in the HTML embed where you have set the group to “Imagen Principal,” try removing that field and just naming it something static like “gallery.” as you are only displaying one lightbox on the page you shouldn’t need to run a dynamic field there. Try that and let me know how you get on.
As a side note, you currently have the lightbox set to the main image within each tab. I personally would have no tabs and just place the four HTML embeds next to each other, you may need to style the thumbnails a little to get everything to line up nicely.
At the moment a customer needs to click on a tab, then click on the larger image to open up the lightbox, that’s one click more than needed. If you get rid of the tabs and just use the HTML embeds, you can display the four thumbnails in a grid, then clicking on them will open up the lightbox.
Let me know how you get on 