[ros-users] Arch Linux Installation Problem

Dear All,
I try to install ros on my linux system (Arch Linux 32bit), I use this
guide http://www.ros.org/wiki/diamondback/Installation/Arch to install
it. but when I digit

rosinstall ~/ros
"http://packages.ros.org/cgi-bin/gen_rosinstall.py?rosdistro=diamondback&variant=desktop-full&overlay=no"




I receive this message:

Traceback (most recent call last):
   File "/usr/bin/rosinstall", line 5, in <module>
     pkg_resources.run_script('rosinstall==0.5.16', 'rosinstall')
   File "/usr/lib/python2.7/site-packages/pkg_resources.py", line 499, 
in run_script
     self.require(requires)[0].run_script(script_name, ns)
   File "/usr/lib/python2.7/site-packages/pkg_resources.py", line 1235, 
in run_script
     execfile(script_filename, namespace, namespace)
   File 
"/usr/lib/python2.7/site-packages/rosinstall-0.5.16-py2.7.egg/EGG-INFO/scripts/rosinstall", 
line 23, in <module>
     import yaml
ImportError: No module named yaml

Since that when I had to use sudo easy_install-2.7 instead sudo
easy_install because "easy_install" doesn't work in my distribution.

Thanks

Andrea