Some Rails Plugins Won't Install

If any of you listening are subversion-savvy, I'm getting the following error when I try and install select plugins:

svn: Can't connect to host '[some hostname]': A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.

...Any clues?

It sure sounds like port-blocking, but I've installed other rails plugins just fine. I suppose it could be the case that the ones that work are using http, but I'm not sure.

I've also tried both hostnames and IP addresses.

...I'm just asking for a little lateral-thinking. If you have any, I'd appreciate it.