Invalid schema generated with <xsd:all> containing element with maxOccurs unbounded value.

I am generating schema from xml instance using the XMLInstance2Schema API.
Schema st_schema =
new XMLInstance2Schema().createSchema(l_reader_xmlInstance);

The input XML instance is

<CONTACT>
<NAME index="1">a</NAME>
<FAX index="1">a</FAX>
<NAME index="1">a</NAME>
<TELEPHONE index="1">a</TELEPHONE>
</CONTACT>

Generated schema is:

<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="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 generated schema contains <xsd:all> with <xsd:element name="NAME" maxOccurs="unbounded">.
where as maxOccurs in <xsd:all> element does not allow unbounded as the value. maxOccurs in xsd:all element allows either 0 or 1 only.
So schema validation is failing in my application.

Please do favour ASAP and thanks in advance.