>> Expecting: ReturnLocations, ReturnServiceInfo, ShipDate
ie all values that appear after the <Height> element. Is there something wrong with the <Height>? Is the XML being truncated?
where is the DTD/Schema defined... can you take a look at it? That error wouldn't happen if those elements are truly optional as the documentation suggests.
Were you me I would be on the phone with USPS... or maybe on hold with USPS (sadLOL)