Problem installing Qt Ruby

I am trying to install Qt Ruby, but am having problems building the
source code. I am running Ruby 1.9.2 on Linux Mint 11 and used these
steps to get it running:
http://torqueo.net/installing-ruby-192-and-rails-3-stable-on-ubuntu/
(I mentioned this because I might have doing something wrong when the
PATH variable, but maybe not)

I first tried using gems, but that didn’t work so I downloaded the
source from: http://rubyforge.org/frs/?group_id=181&release_id=44227. I
tried using the cmake command, but then got this error:

CMake Error at cmake/modules/FindRUBY.cmake:85 (MESSAGE):
Could not find Ruby
Call Stack (most recent call first):
CMakeLists.txt:77 (FIND_PACKAGE)

– Configuring incomplete, errors occurred!

I’m not sure what is causing this error. Could it be that it is not
compatible with my version of Ruby? I searched this problem, and someone
mentioned it could be because I didn’t have the Ruby development
packages, but I couldn’t find them for Ruby 1.9.2?

Any help would be very appreciated. Thanks.