When I hit to use the Command-T extension in VIM, I get the error

command-t.vim could not load the C extension

I'm not sure how to go about fixing this... any suggestions?

Thanks

I am using the git-repository installation method.
Here's what happens when I "rake make":

~/.vim/bundle/command-t$ rake make

(in /home/petef/.vim/bundle/command-t)

/usr/bin/ruby1.8 extconf.rb

extconf.rb:24:in `require': no such file to load -- mkmf (LoadError)

    from extconf.rb:24

rake aborted!

Command failed with status (1): [/usr/bin/ruby1.8 extconf.rb...]

/home/petef/.vim/bundle/command-t/Rakefile:136

(See full trace by running task with --trace)