invalid xsd schema generated from the instance

when i give the following xml instance for converting using xmlInstance2schema generator
<CONTACT>
<NAME index="1">a</NAME>
<DESCRIPTN>a</DESCRIPTN>
<EMAIL>a</EMAIL>
<FAX index="1">a</FAX>
<NAME index="1">a</NAME>
<TELEPHONE index="1">a</TELEPHONE>
</CONTACT>

the instance has NAME element repeated 2 times.
to the schema

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<xsd:element name="CONTACT">
<xsd:complexType>
<xsd:all>
<xsd:element name="NAME" maxOccurs="unbounded">
<xsd:complexType mixed="true">
<xsd:sequence/>
<xsd:attribute name="index" type="xsd:integer"/>
</xsd:complexType>
</xsd:element>
<xsd:element name="DESCRIPTN" type="xsd:string"/>
<xsd:element name="EMAIL" type="xsd:string"/>
<xsd:element name="FAX">
<xsd:complexType mixed="true">
<xsd:sequence/>
<xsd:attribute name="index" type="xsd:integer"/>
</xsd:complexType>
</xsd:element>
<xsd:element name="TELEPHONE">
<xsd:complexType mixed="true">
<xsd:sequence/>
<xsd:attribute name="index" type="xsd:integer"/>
</xsd:complexType>
</xsd:element>
</xsd:all>
</xsd:complexType>
</xsd:element>
</xsd:schema>

the problem with the above schema is that all element cannot have a child element that can occur more than 1.
when i use other tools like trang it is generating properly with have choice instead of the all element