Self reference in an element

Hi Sir,

       I am writing an schema for the following structure:

Organization
    dept +
        @num
        name
        total_emp
        dept +
where dept elements are nested within another dept element, but all
departments are under organization.


My Schema is:


<xs:schema xmlns:ns1="http://www.ns1.com"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://www.ns1.com">
	<xs:element name="Organization">
		<xs:complexType>
			<xs:sequence>
				<xs:element name="Department" maxOccurs="unbounded">
					<xs:complexType>
						<xs:sequence>
							<xs:element name="Name"/>
							<xs:element name="TotalEmp"/>
							<xs:element ref="ns1:Department" minOccurs="0" maxOccurs="unbounded"/>
						</xs:sequence>
						<xs:attribute name="num" type="xs:string"/>
					</xs:complexType>
				</xs:element>
			</xs:sequence>
		</xs:complexType>
	</xs:element>
</xs:schema>


There is a validation error saying "ns1:Department" is not a QName and
cannot find declaration for the same. Is there something wrong in my
definition?


Can you please let me know whether it is a correct approach or wrong?


Thanks,

Avinash K N