After reviewing your actual XML - it looks like your XPath is incorrect for your intentions. I don't see any attriubes in your XML.
in reply to Re^2: Xml::Twig:Xpath Xpath expression error
in thread Xml::Twig:Xpath Xpath expression error
Try something more like
to reference your information.
The previous XPath's are attempting to search for attributes in the FlowRater node. What you actually have is a child node called Name with some information in it.
As far as why this works in some modules, and not in others I would postulate that the designer included this as a "feature" to help others out. - Or maybe you found a bug.