Don't know if this will mean much to anyone, but I wasted an entire morning painfully trying to figure this out.
I've been upgrading my management systems to the new Yahoo Search API, and also working with v8 of the AdWords API. I'm no master of SOAP/WSDL so I tend to work with the software examples they give (for Perl).
Well, the Yahoo Search API needs SOAP::Lite 0.69 whether or not you use Yahoo::Marketing or do it yourself. Unfortunatly, there are issues with SOAP::Lite over 0.65 for Google's API.
I'm (unfortunately) on Windows. 0.55 comes with ActiveState and works with Google. You can upgrade to 0.69 from the trouchelle repository, but as soon as you do that Google will break.
Here was my solution. Install 0.69 to another directory and put "use lib \path\" in your Yahoo application. That worked.
If this will spare anyone else the morning I had then all the best to you.