New Added Regions Appearing in Admin/Block page but not main site.

Issue Summary

I've created a new region for my theme recently, to hold some ads but these are only appearing in the admin block page.

I've assigned a test block to the region but on the main site they don't appear. I've added the correct php to the page.tpl.php file, and have updated my .info file accordingly.

All caches/registry have been flushed, and have also tried disabling and re-enabling the theme but to no avail. Have also tried to create a new theme, and quickly added new regions to that, but still no joy.

I do have a few regions already added to my theme but for some reason they're not working when I add new regions now.

Since adding the new region, the only thing that might be different is that I tested some caching modules, but have since disabled these, and emptied their tables in the database.

Any help on this would be greatly appreciated.