I'm having quite a bit of trouble with installing themes on WP Multisite, which I've never come across before.
Basically, I install a brand new, clean version of WPMU and all seems fine. I can install a few themes at this point and they tend to work ok.
But then, later on, perhaps days later, once I've started working on the rest of the site and put up a few pages and posts, it all goes wrong. When I install a few extra themes, simply by copying them into the themes folder as normal, wordpress just wont find them. I've checked and double checked they're in the right place - I've worked with single-site WP for a while now so I've got a good idea of how it all works - and all seems absolutely fine, but WP just wont recognise that they're there.
Any ideas would be greatly appreciated - it's driving me crazy...