"File not found: lib" when switching to older rails version using RVM

I currently have rails 3.0.3 and am trying to download and use version 3.0.1. I've downloaded 开发者_开发知识库and installed RVM and inputted the following code in Terminal (I have a Mac OS X 10.6.5):

rvm use 1.8.7
rvm gemset create rails3.0.1
rvm 1.8.7@rails3.0.1
sudo gem install rails --version=3.0.1

I use sudo gems because of the user permissions, or my lack there of. Anyway, after I enter the last line of code: "sudo gem install rails --version=3.0.1" I get the following error:

Successfully installed rails-3.0.1
1 gem installed
Installing ri documentation for rails-3.0.1...
File not found: lib

Not only can I apparently not able to switch versions of rails, even though it appears as though I have multiple versions installed, every time I try to check to see what version of rails I currently have I get the following result:

rails -v
/Library/Ruby/Site/1.8/rubygems.rb:779:in `report_activate_error': Could not find  RubyGem rails (>= 0) (Gem::LoadError)
from /Library/Ruby/Site/1.8/rubygems.rb:214:in `activate'
from /Library/Ruby/Site/1.8/rubygems.rb:1082:in `gem'
from /usr/bin/rails:18

Also, I've already installed Rdoc and Xcode (I've done research and other suggestions pointed to installing both). I'm a RoR newbie, and especially an RVM newbie, so I would love an explanation and a solution to this madness.

Thank you for reading!

---

I think you went off the rails (ha-ha) right here:

sudo gem install rails --version=3.0.1

The RVM documentation has this to say about that:

DO NOT use sudo...

to work with RVM gems. When you do sudo you are running commands as root, another user in another shell and hence all of the setup that RVM has done for you is ignored while the command runs under sudo (such things as GEM_HOME, etc...). So to reiterate, as soon as you 'sudo' you are running as the root system user which will clear out your environment as well as any files it creates are not able to be modified by your user and will result in strange things happening. (You will start to think that someone has a voodoo doll of your application...)