[ruby] rvm installation not working: "RVM is not a function"

I just installed RVM, but can't make it work. I have such line at the end of my .profile file:

[[ -s "$HOME/.rvm/scripts/rvm" ]] && . "$HOME/.rvm/scripts/rvm"

I tried to run source .profile and restarting terminal, but still, when I run rvm use 1.9.2 I'm getting:

RVM is not a function, selecting rubies with 'rvm use ...' will not work.

My system is Ubuntu 11.10.