using expand_dl error

Hello, here I need some help.
I want use expand_dl to exposes the distribution group,but ruby warned me "undefined method `expand_dl'".So I add "include Viewpoint::EWS::SOAP::ExchangeDataServices", but ruby still warned me "undefined method `build_soap!'".
Now I can't find where is `build_soap!',  so how can i use expand_dl method?
I will be thankful if you could answer it.