What is wrong with this XPath Expression in a jaxb bindings file?

trying to evaluate the XPath expression /xs:schema/xs:element[@name='StrikeOptionReservationSummaryData']/xs:complexType

with the following document produces an XPathExpressionException

<xs:schema>

<xs:element name="StrikeOptionReservationSummaryData">

<xs:complexType>

...

</xs:complexType>

</xs:element>

<xs:schema>

The error from from xjc is [ERROR] XPath error: null

What is wrong with this?

It's a lousy diagnostic, but perhaps you didn't give the XPath processor a binding for the namespace prefix "xs"?