XQuery assert generates an error

I am getting a java error RuntimeException:java.lang.reflect.InvocationTargetException

when configuring XQuery assert.

 

Just a trivial query

{
for $x in //ns0:Fees/ns0:Fee
return {data($x/ns0:feeType/text())}

}

with all namespaces declared.

The excat error when clicking test button

XQuery Match Assertion failed for path [declare namespace ns0='http://www.tibco.com/schemas/DBAFeeCalculator/SharedResources/XSD/Schema.xsd'; { for $x in //ns0:Fees/ns0:Fee return {data($x/ns0:feeType/text())} }] : RuntimeException:java.lang.reflect.InvocationTargetException

 

Any clues?

Thank you