xs:include change base type

I would like to extend an xs:complexType, and change one of its
attributes from a type xs:NCName to xs:simpleType, with the same base
type mind you.  So something like this:


<xs:complextType name="myComplexType">
  <xs:sequence>...</xs:sequence>
  <xs:attribute name="name" type="xs:NCNAME"/>
</xs:complexType>


Then...

<xs:complexType name="myNewComplexType">
<xs:complexContent>
  <xs:extension base="myComplextType">
     <xs:attribute name="name" type="some_simple_type"/>
  </xs:extension>
</xs:complexContent>
</xsl:complexType>


Is this possible?  I've tried but having no luck.