Saxon

I am using some software to compare OpenOffice documents. It uses Saxon PE, and with a particular document (of which I have attached a very simplified version) it is throwing the following exception when I compare it with itself:

com.deltaxml.odf.comp.OdtComparatorException: An error occurred while comparing styles. Comparison a
borted.
        at com.deltaxml.odf.comp.OdtComparator.compare(Unknown Source)
        at com.deltaxml.odf.comp.OdtComparator.compare(Unknown Source)
        at com.deltaxml.odf.comp.OdtComparatorDriver.odt_c_a(Unknown Source)
        at com.deltaxml.odf.comp.OdtComparatorDriver.main(Unknown Source)
Caused by: com.deltaxml.odt_c_e.odt_c_g: Filter runtime exception for the filter at position 7 in th
e input a filter chain (filter: jar:file:/C:/Program%20Files/DeltaXML-ODT-Compare-2_4/deltaxml-odt-c
ompare.jar!/comp-xsl/odt-list-styles-infilter.xsl.crypt)
        at com.deltaxml.odt_c_e.odt_c_a.odt_c_b.odt_c_a(Unknown Source)
        at com.deltaxml.odt_c_e.odt_c_a.odt_c_b.odt_c_a(Unknown Source)
        at com.deltaxml.odt_c_e.odt_c_u.run(Unknown Source)
        at com.deltaxml.odt_c_e.odt_c_q.odt_c_a(Unknown Source)
        at com.deltaxml.odt_c_e.odt_c_q.odt_c_a(Unknown Source)
        ... 4 more
Caused by: net.sf.saxon.trans.XPathException: An empty sequence is not allowed as the value of varia
ble $list-style
        at net.sf.saxon.expr.CardinalityCheckingIterator.typeError(CardinalityCheckingIterator.java:
121)
        at net.sf.saxon.expr.CardinalityCheckingIterator.(CardinalityCheckingIterator.java:48)

        at net.sf.saxon.expr.CardinalityChecker.iterate(CardinalityChecker.java:171)
        at net.sf.saxon.expr.instruct.Choose.iterate(Choose.java:826)
        at net.sf.saxon.expr.PathExpression.iterate(PathExpression.java:619)
        at net.sf.saxon.expr.FilterExpression.iterate(FilterExpression.java:1111)
        at net.sf.saxon.expr.instruct.ForEach.processLeavingTail(ForEach.java:344)
        at net.sf.saxon.expr.LetExpression.processLeavingTail(LetExpression.java:559)
        at net.sf.saxon.expr.instruct.Choose.processLeavingTail(Choose.java:758)
        at net.sf.saxon.expr.LetExpression.processLeavingTail(LetExpression.java:559)
        at net.sf.saxon.expr.instruct.Block.processLeavingTail(Block.java:569)
        at net.sf.saxon.expr.instruct.Template.applyLeavingTail(Template.java:208)
        at net.sf.saxon.expr.instruct.ApplyTemplates.applyTemplates(ApplyTemplates.java:368)
        at net.sf.saxon.expr.instruct.ApplyTemplates.apply(ApplyTemplates.java:232)
        at net.sf.saxon.expr.instruct.ApplyTemplates.process(ApplyTemplates.java:192)
        at net.sf.saxon.expr.instruct.ElementCreator.processLeavingTail(ElementCreator.java:318)
        at net.sf.saxon.expr.instruct.Copy.processLeavingTail(Copy.java:366)
        at net.sf.saxon.expr.instruct.Template.applyLeavingTail(Template.java:208)
        at net.sf.saxon.expr.instruct.ApplyTemplates.applyTemplates(ApplyTemplates.java:368)
        at net.sf.saxon.expr.instruct.ApplyTemplates.apply(ApplyTemplates.java:232)
        at net.sf.saxon.expr.instruct.ApplyTemplates.process(ApplyTemplates.java:192)
        at net.sf.saxon.expr.instruct.ElementCreator.processLeavingTail(ElementCreator.java:318)
        at net.sf.saxon.expr.instruct.Copy.processLeavingTail(Copy.java:366)
        at net.sf.saxon.expr.instruct.Template.applyLeavingTail(Template.java:208)
        at net.sf.saxon.expr.instruct.ApplyTemplates.applyTemplates(ApplyTemplates.java:368)
        at net.sf.saxon.trans.StringifyRuleSet.process(StringifyRuleSet.java:54)
        at net.sf.saxon.expr.instruct.ApplyTemplates.applyTemplates(ApplyTemplates.java:356)
        at net.sf.saxon.Controller.transformDocument(Controller.java:1887)
        at net.sf.saxon.Controller.transform(Controller.java:1737)
        at net.sf.saxon.s9api.XsltTransformer.transform(XsltTransformer.java:402)
        at com.deltaxml.odt_c_e.odt_c_a.odt_c_b.odt_c_a(Unknown Source)
        at com.deltaxml.odt_c_e.odt_c_a.odt_c_b.odt_c_a(Unknown Source)
        ... 9 more

The version of Saxon PE that they have supplied is 9.3.0.4J. I can see that 9.3.0.11J is available from http://www.saxonica.com/download/information.xml, but if I replace the JAR file I get the error "The installed license (serial number XXXXXXX) does not cover this Saxon maintenance release". I was wondering if anybody could tell me whether this is something that would be fixed in the later version, or if it's actually the case that the XML in the document is invalid in some way. Thanks in advance.