heroku - Heroku error can't login

Question

I'm using a mac with leopard 10.5.8 after installing the Heroku Toolbelt, I type in the Terminal the command Heroku but I end up with this message:

> /usr/local/heroku/vendor/gems/heroku-api-0.2.13/lib/heroku/api.rb:3:in `require': no such file to load -- securerandom (LoadError)
    from /usr/local/heroku/vendor/gems/heroku-api-0.2.13/lib/heroku/api.rb:3
    from /usr/local/heroku/vendor/gems/heroku-api-0.2.13/lib/heroku-api.rb:1:in `require'
    from /usr/local/heroku/vendor/gems/heroku-api-0.2.13/lib/heroku-api.rb:1
    from /usr/local/heroku/lib/heroku/cli.rb:7:in `require'
    from /usr/local/heroku/lib/heroku/cli.rb:7
    from /usr/bin/heroku:22:in `require'
    from /usr/bin/heroku:22