Xerces not reporting validation errors ?

I am validating an XML doc in Java with Xerces, but don't get any errors.
However, the XML doc contains errors and when I validate it with for example
XMLSply editor, the errors are correctly reported.
I can't find what I am doing wrong. I think I do include all XSD schemas
that are required to validate correctly.

Please some advice? The code snippet:
-----
SchemaFactory factory =
SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
factory.setErrorHandler(new ErrorHandlerDefault());
Schema schema = factory.newSchema(createSchemaSources());
validator = schema.newValidator().validate("file.xml";
----

The XSD's that I use to validate:
---------
private Source[] createSchemaSources() throws IOException {
 Source[] sources = new Source[5];
 sources[0] =
createSource("http://www.nltaxonomie.nl/7.0/domein/bd/tuples/bd-bedr-tuples.
xsd");
 sources[1] =
createSource("http://www.nltaxonomie.nl/7.0/domein/bd/tuples/bd-bedr-tuples.
xsd");
 sources[2] =
createSource("http://www.nltaxonomie.nl/7.0/domein/bd/tuples/bd-burg-tuples.
xsd");
 sources[3] =
createSource("http://www.nltaxonomie.nl/7.0/basis/sbr/types/nl-types.xsd");
 sources[4] =
createSource("http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd");
return sources;
}
----------

A small snippet of the xml file being validated (too big to list all):
---------
 <bd-burgers:CommutingExpensesDaysPerWeekCount unitRef="uu_513"
contextRef="cc_711">2</bd-burgers:CommutingExpensesDaysPerWeekCount>
----------
This entry contains an error, namely:
  Numeric item <bd-burgers:CommutingExpensesDaysPerWeekCount> has neither a
'precision' nor a 'decimals' attribute.

This is correctly reported by XMLSpy but not by my Java code :(... So what
am I doing wrong here? I though I was forgetting an XSD file, but
"CommutingExpensesDaysPerWeekCount" is defined in
"http://www.nltaxonomie.nl/7.0/basis/bd/items/bd-burgers.xsd", that is
contained int he above xsd's, that corresponds to the type
"nonNegativeIntegerItemType" contained in
"http://www.nltaxonomie.nl/7.0/basis/sbr/types/nl-types.xsd", also contained
in the xsd's above, and that extends "monetaryItemType" and is defined in
"http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd", which xsd is also
contained in the above validation.

Any idea why my Java validation not reports any errors?

BTW: it does report an error if I change the above XML snippet in:

-----
 
<bd-burgers:CommutingExpensesAccordingToTableTotalAmount>841.0</bd-burgers:C
ommutingExpensesAccordingToTableTotalAmount>
----
That is: removing all attributes. I then get a correct Validation error
saying that the contextRef is missing.

- Ed