java.lang.InternalError: unresolved reference

[raedtjr]

When trying to map a specific xsd file I got an exception which I can not solve.
Exception in thread "main" java.lang.InternalError: unresolved reference at com.sun.xml.xsom.impl.parser.DelayedRef._get(DelayedRef.java:103) at com.sun.xml.xsom.impl.parser.DelayedRef$Element.get(DelayedRef.java:199) at com.sun.xml.xsom.impl.ElementDecl.getSubstAffiliation(ElementDecl.java:115) at com.sun.xml.xsom.impl.ElementDecl.updateSubstitutabilityMap(ElementDecl.java:179) at com.sun.xml.xsom.impl.parser.ParserContext.getResult(ParserContext.java:141) at com.sun.xml.xsom.parser.XSOMParser.getResult(XSOMParser.java:214) at tr.com.srdc.ontmalizer.XSD2OWLMapper.parseXSD(XSD2OWLMapper.java:128) at tr.com.srdc.ontmalizer.XSD2OWLMapper.<init>(XSD2OWLMapper.java:96) at test.main(test.java:13)
the xsd file is quite big and includes some import. I can share it in case it is required.
Any help would be much appreciated.