xrefresh-server error (10.6.2 using MacPorts)

Here is my setup (pretty much 'latest' everything):

OS X 10.6.2.
Firefox 3.6.
XRefresh 1.4.
Ruby 1.9.1p376 installed via MacPorts using the +nosuffix variant.
Rubygems 1.3.5 with :sources => ["http://gemcutter.org", "http://gems.rubyforge.org/"]
RubyCocoa 1.0.1 installed from binary release.

Here is my error message:

/opt/local/lib/ruby/gems/1.9.1/gems/xrefresh-server-0.3.0/bin/../lib/xrefresh-server.rb:9:in `': uninitialized constant PLATFORM (NameError)
from /opt/local/lib/ruby/gems/1.9.1/gems/xrefresh-server-0.3.0/bin/xrefresh-server:15:in `require'
from /opt/local/lib/ruby/gems/1.9.1/gems/xrefresh-server-0.3.0/bin/xrefresh-server:15:in `'
from /opt/local/bin/xrefresh-server:19:in `load'
from /opt/local/bin/xrefresh-server:19:in `'

I suspect maybe this has something to do with the part in RubyCocoa's ReadMe saying:

"If you overwrote Apple's Ruby with a custom version, please make sure that it has been built with --enabled-shared", which is something I don't know how to achieve when installing Ruby from MacPorts. Then again, I'm not sure if this is the reason why I get this error message when trying to use xrefresh-server. (I noticed also, that I have a command called xrefresh only, i.e. not xrefresh-server, which I don't know where it comes from. When running that command, simply nothing happens.)