I migrated to 1.8.7 Ruby and now I keep getting this error and it is driving me crazy. I try installing it manually using gem install soap4r and also include it as a config.gem
Try to load it as
require 'soap4r' in your code
And make sure you installed soap4r with all the dependencies
here is a link for how to install it - http://www.tutorialspoint.com/ruby/ruby_web_services.htm
cheers
sameera