I don’t think it’s a good idea to manually remove an XML namespace, they are there for a reason.
to the original problem: the XPath so far is correct, but the od namespace must be known to the XPath interpreter (which obviously depends on the interpreter used, XSLT is different from SimpleXML is different from DOMDocument, etc.)
the return type of the XPath expression is usually a string for primitive data types (maybe except for the XPath functions), though that may also depend on the interpreter used.
The computer is always right. The computer is always right. The computer is always right. Take it from someone who has programmed for over ten years: not once has the computational mechanism of the machine malfunctioned.
André Behrens, NY Times Software Developer