oasis xml catalog. how to use?

hi,

does someone have an idea why the line defining my catalog
is not read?
My catalog file is located in the same directory as my sample.xml

I am using Xerces SAXParser 2.4.0

Is there something special to do so that the catalog declaration
is taken into account when the parser is in action?



<!-- Content of sample.xml  -->
<?xml version="1.0"?>
<?oasis-xml-catalog catalog="./catalog.xml"?>

<!DOCTYPE Book SYSTEM "http://www.site.com/Book.dtd">
<Book>
	...
</Book>


Thanks for your help.



Richard