I found a previous thread with exactly the same problem.as described by siriosrl: forum.joomlaworks.net/simple-image-gallery-pro-%28plugin%29/gallery-doesn%27t-work-with-gallery-layout-in-any-popup-engine/

Thumbs and gallery work as expected - all thumbs are displayed correctly and clicking any thumb brings up its correct image in gallery.
Clicking on an image in the gallery displays a 'lightbox' (modal popup) which shows ONLY the image clicked in the gallery.
And only 1 thumb shows in popup, and there are no prev|next|whatever buttons for other images in the Gallery

also as siriosrl in other thread I have tried with ALL popup engines

Using J! 2.5.6 with latest sigpro
There are no relevant errors in server log
No js errors in firebug

edit: Issue is the same in FF 13|14 and chrome 21 in fedora or windows and ie8

I only have this on localhost and need this to work before it goes live so I need suggestions as to what was the fix, or where to look for pointers to source of problem please?

thanks

oh yea: If you dont get the captcha right when submitting this form the data is lost. luckily I have an obsessive compulsion to keep hitting ctrl-a ctrl-c

Check Galleria template in the demo site please...
This is how it works!

oh  :(
...sad face - like your avatar!

Yea I did see the gallery - and I saw this combination:

Classic gallery layout - using default plugin settings, overriding caption handling (set to none) and using the PrettyPhoto popup engine

[url=http://demo.joomlaworks.net/simple-image-gallery-pro#!prettyPhoto[gallery97b6b06ad9]/0/]demo.joomlaworks.net/simple-image-gallery-pro#!prettyPhoto[gallery97b6b06ad9]/0/[/url]

and because SIGPro has such a bewildering array of options I assumed Galleria would work with PrettyPhoto

Its disappointing it doesnt - but it looks like it almost works?
I attach screenshot - prev|next and thumbnail are there already, surely it just needs a list of images to display!

And that must be well within your considerable skills to make it work - isnt it?

please tell me you can make it work...?

Sorry, but I am afraid not...
What you can do is using a different SIG PRO template closer to what you are looking for...