Not sure about the metasploit tutorial but normally you have to add a gems repository if its a non standard one. Here is the github for gems and some instructu=ions on how to do it once you locate the proper repo.
GitHub RubyGems
On the Metasploit Unleashed Wiki under the Karmetasploit instructions it has you install some ruby gems as such :
My persistant usb installed backtrack4 machine spits out this errorCode:gem install activerecord sqlite3-ruby
Any help would be greatly appreciated.ERROR: could not find gem activerecord locally or in a repository
ERROR: could not find gem sqlite3-ruby locally or in a repository
Not sure about the metasploit tutorial but normally you have to add a gems repository if its a non standard one. Here is the github for gems and some instructu=ions on how to do it once you locate the proper repo.
GitHub RubyGems
I just tried it on another BT4 install and it worked fine. I must have borked something in this install.