Hallo wmUsers!

I have a problem with importing an XML-schema, which contains an attribute reference to xml:lang.

The schema looks as follows (basically):

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema 
xmlns="http://xyz.com/Examp" 
xmlns:xs="http://www.w3.org/2001/XMLSchema" 
targetNamespace="http://xyz.com/Examp"
elementFormDefault="qualified">

<xs:import namespace="http://www.w3.org/XML/1998/namespace"/> <!-- ** -->

<xs:element name="Examp">
<xs:complexType>
<xs:sequence>
<xs:element name="Text">
<xs:complexType>
<xs:simpleContent>
<xs:extension base="xs:string">
<xs:attribute ref="xml:lang" use="required"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>

So a valid XML document would look like

<?xml version="1.0" encoding="UTF-8"?>
<Examp xmlns="http://xyz.com/Examp">
<Text xml:lang="en-us">Hello space!</Text>
</Examp>

Now, if I want to create a DocumentType from that schema, (after quite some waiting) the Developer throws the error:

Success: false

Error: 0
identifier: /schema/element[@name="Examp"]

source: -----   Source   -----
<xs:attribute ref="xml:lang" use="required"/>

errorMessage: [ISC.0082.9706] Declaration not found

What could be the problem here and how could I solve it, so that I can at the successfully validate an XML document containing the xml:lang attribute?

Thx, Christoph

PS:
I also tried modifying the schema, with the import-line looking as follows:

<xs:import namespace="http://www.w3.org/XML/1998/namespace" schemaLocation="http://www.w3.org/2001/xml.xsd"/>

or

<xs:import namespace="http://www.w3.org/XML/1998/namespace" schemaLocation="C:\xml\Schema\xml.xsd"/>

or
by even leaving the import-line away.

But none of it worked.