multiple attributes in a simple type within agroup

Hi I'm having problems validating my schema and xsd files I think there maybe a problem placing multiple attributes in a simple type within a group below is my code

xsd:

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<!--definition of an element group -->
<xsd:group name="computerFeatures">
<xsd:sequence>
<!--definition of simple type elements -->
<xsd:element name="cpu" type="xsd:string" minOccurs="1" maxOccurs="1"/>
<xsd:element name="memory" type="xsd:string" minOccurs="1" maxOccurs="1"/>
<xsd:element name="hd" type="xsd:string" minOccurs="1" maxOccurs="1"/>
<xsd:element name="drive" type="xsd:string" minOccurs="1" maxOccurs="1"/>
<xsd:element name="video" type="xsd:string" minOccurs="1" maxOccurs="1"/>
<xsd:element name="modem" type="xsd:string" minOccurs="1" maxOccurs="1"/>
</xsd:sequence>
</xsd:group>

<xsd:group name="computerOptions">
<xsd:sequence>
<!--definition of simple type elements -->
<xsd:element name="airport" type="xsd:string" minOccurs="1" maxOccurs="1"/>
<xsd:attribute ref="picture">
<xsd:attribute ref="price">
</xsd:element>

<xsd:element name="ipod" type="xsd:string" minOccurs="1" maxOccurs="1"/>
<xsd:complexType>
<xsd:attribute ref="picture">
<xsd:attribute ref="price">
</xsd:complexType>
</xsd:element>

<xsd:element name="app" type="xsd:string" minOccurs="1" maxOccurs="1"/>
<xsd:complexType>
<xsd:attribute ref="picture">
<xsd:attribute ref="price">
</xsd:complexType>
</xsd:element>

</xsd:sequence>
</xsd:group>

<!--definition of attributes-->
<xsd:attribute name="storeName" type="xsd:string"/>
<xsd:attribute name="picture" type="xsd:string"/>
<xsd:attribute name="price" type="xsd:float"/>
<xsd:attribute name="tax" type="xsd:float"/>
<xsd:attribute name="shipping" type="xsd:float"/>

<!--definition of complex type elements -->
<xsd:element name="model">
<xsd:complexType>
<xsd:sequence>
<xsd:group ref="computerFeatures" minOccurs="1" maxOccurs="1"/>
<xsd:group ref="computerOptions" minOccurs="1" maxOccurs="1"/>
</xsd:sequence>
<xsd:attribute name="picture" type="xsd:string"/>
<xsd:attribute name="price" type="xsd:float"/>
<xsd:attribute name="tax" type="xsd:float"/>
<xsd:attribute name="shipping" type="xsd:float"/>
</xsd:complexType>
</xsd:element>

<xsd:element name="computerStore">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="model" minOccurs="0" maxOccurs="unbounded"/>
</xsd:sequence>
<xsd:attribute name="storeName" type="xsd:string"/>
<xsd:attribute ref="picture"/>
</xsd:complexType>
</xsd:element>
</xsd:schema>

xml file:

<?xml version="1.0" encoding="UTF-8"?>

<computerStore storeName="Mac Store">
<model picture="imac.jpg" price="799" tax="0.14" shipping="20" >
<cpu>600MHz PowerPC G3</cpu>
<memory>128MB SDRAM</memory>
<hd>40GB Ultra ATA drive</hd>
<drive>CD-ROM</drive>
<video>Rage 128 Ultra graphics</video>
<modem>56K internal modem</modem>
<options>
<airport picture="airport.gif">AirPort</airport>
<ipod picture="ipod.gif">iPod</ipod>
<app picture="app.gif">Apple Protection Plan</app>
</options>
</model>
</computerStore>

I been validating the two files at http://www.xmlforasp.net/content.as...SchemaValidator

Can anyone tell me whats wrong with my xsd

Thanx
getchoo

Double check your closing tags. You've got some <xsd:element> tags that close with />, that later have a closing tag </...>