Modal PopUp only flashes up and dissapears again (no input possible)

The most common cause of the popup appearing and vanishing is if the Bootstrap Javascript library is included twice on the page. The easiest solution is to enable our "Include jQuery / Bootstrap" setting, which includes a very specific version of those files just for our extensions.

Beyond that, we'd definitely need to see the problem to help investigate further. Can you PM or post the URL for us to have a look? You can PM me by clicking the mail icon under my name to the left.

Thanks,
Alex

On your site, there's an element called #galleryOverlay that's taking up the whole page and has a z-index of 100000. That's higher than the z-index we set on our SCLogin module. To fix, you'll need to either:
* Remove that element
* Decrease it's z-index to something under 1100, which is what your template is setting our modal popup to
* Increase the div.modal.fade.in z-index setting in your template to something larger than 100000

I hope that helps,
Alex