Wiki setup failed somewhere in WP/Filezilla/WPMU interface

I'm trying to install the WPMU wiki (full version) in a WP site hosted at Laughing Squid. I think I've managed to get all the wiki files into the correct folder (wp-content/plugins), at least according to my listing in Filezilla, but the files showing in the Laughing Squid control panel list are different from those showing when I look at the Filezilla listing. So something is off-base somewhere, it seems.

Also, the last time I was able to look at my WP Dashboard, the wiki plugin was actually showing up in the plugin list, but when I clicked "Activate," it took me to a completely blank screen, and now when I try to access the WP site (homepage or Dashboard) I also get a blank screen.

Any thoughts will be most welcome!