As soon as I input the url for our meetup site, I got a page full of errors, all beginning with
Warning: SimpleXMLElement::__construct() [simplexmlelement.--construct]: ^
and at the bottom of a long list
Fatal error: Uncaught exception 'Exception' with message 'String could not be parsed as XML'
Mark, I've saved the full page of errors; if it's helpful for your debugging I can email it to you.