Namespace issue

Hello there,
I am trying to generate an XSD with an XML instance. For this XML
Instance,

<?xml version="1.0" encoding="UTF-8"?>
<abc:io
xmlns:abc="urn:com.mycompany:bizatoms">
    <abc:array>
<abc:string>Data posted</abc:string>
    </abc:array>
</abc:io>

The generated
Schema was

<?xml version="1.0" encoding="utf8"?>
<?bpc.pltype.out
bpm.pltype=xsd,bpm.pltype=xml?>
<xs:schema
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:abc="urn:com.mycompany:bizatoms"
targetNamespace="urn:com.mycompany:bizatoms" elementFormDefault="qualified"
attributeFormDefault="unqualified">
    <xs:element name="io">
<xs:complexType>
            <xs:sequence>
                <xs:element
name="array" type="arrayType"/>
            </xs:sequence>
</xs:complexType>
    </xs:element>
    <xs:complexType name="arrayType">
<xs:sequence>
            <xs:element name="string" type="stringType"/>
</xs:sequence>
    </xs:complexType>
    <xs:simpleType name="stringType">
<xs:restriction base="xs:string"/>
    </xs:simpleType>
</xs:schema>

I get an
error while valididating the Schema : 'stringType' must refer to an 
existing
simple or complex type.

I am not able to understand why this error pops up..
although the type is 
defined and it is under the same namespace.

Can someone
highlight on this particular case, and suggest how would the schema 
be
"pre-fixed perhaps?"

thank you
Densil