Notation problems: parser reports undeclared although it is declared in my schema

Hi There!

Need some help with a Notation problem:

As long as this line is in my xml the doument parses just fine:

<!NOTATION cgm PUBLIC '-//USA-DOD//NOTATION Computer Graphics Metafile//EN'>

I use Arbortext Editor as an editor, it removes the the line above and 
when reparsed I get the following parse error:
--
The notation "cgm" must be declared when referenced in the unparsed 
entity declaration for "A-CGM-GRAPHIC".
--

This might sound reasonable, but it's not, because the notation is 
declared in my schema like this:
<xs:notation name="cgm" public="-//USA-DOD//NOTATION Computer Graphics 
Metafile//EN"/>
I've tried validating the file in XMLSpy and it is quite happy and 
reports no errors.
Any ideas why xerces will not parse my doc?

I'm using Xerces 2.7.1 ....

--
Espen Ø. Pedersen