non-deterministic content model using groups

Could someone tell me why the schema below exhibits a
non-deterministic content model for any of the
elements in the "audio" or "video" groups?  

<?xml version="1.0" encoding="utf-8"?>
<xsd:schema
xmlns:xsd="http://www.w3.org/2001/XMLSchema">
	<xsd:element name="content-item">
		<xsd:complexType>
			<xsd:sequence>
				<xsd:group ref="item-types"/>
			</xsd:sequence>
		</xsd:complexType>
	</xsd:element>
	<xsd:group name="item-types">
		<xsd:sequence>
			<xsd:choice>
 				<xsd:group ref="audio"/>
				<xsd:group ref="video"/>
				</xsd:choice>
		</xsd:sequence>
	</xsd:group>
	<xsd:group name="video">
		<xsd:all>
			<xsd:element name="relationship" type="xsd:string"
/>
			<xsd:element name="url" type="xsd:string"/>
			<xsd:element name="speed" type="xsd:integer"/>
			<xsd:element name="headline" type="xsd:string"/>
		</xsd:all>
	</xsd:group>
	<xsd:group name="audio">
		<xsd:all>
			<xsd:element name="relationship" type="xsd:string"
/>
			<xsd:element name="url" type="xsd:string"/>
			<xsd:element name="kicker" type="xsd:string" />
			<xsd:element name="headline" type="xsd:string"/>
		</xsd:all>
	</xsd:group>
</xsd:schema>

=====
--
Richard von Keyserling
201.838.5751
--

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Received on Wednesday, 1 May 2002 04:53:58 UTC