generate_message is not supported

[terenced]

I followed the example found in the wiki 5) Create new emails!

email = gmail.generate_message do
  to "email@example.com"
  subject "Having fun in Puerto Rico!"
  body "Spent the day on the road..."
end

but I get the following error:
undefined method `generate_message' for #Gmail::Client::Plain:0x007f94813a5fa8 (NoMethodError)

Ruby 1.9.3p125 (2012-02-16 revision 34643) [x86_64-darwin11.3.0]
Mac OS X 10.7.5

[matsubo]

+1

[myobie]

The method does exist. Can you give me a longer code example?

[MaxRumpf]

I get that error too.

[MaxRumpf]

Does it have any Dependency else than "gmail" ?