Loop in Schema defination

I have a XML structure where an element has two forms occuring at two levels.

<Collection>
<MyObject>
<DisplayTitle> Title Level 1 </DisplayTitle>
<SubCollection>
<MyObject>
<DisplayTitle> Title Level 2 </DisplayTitle>
</MyObject>
<MyObject>
.....
</MyObject>
<MyOtherObject> Some Information </MyOtherObject>
</SubCollection>
</MyObject>
<MyObject>
......
</MyObject>
</Collection>

If I define a schema for this structure I get two forms for MyObject:

At Level 1
<xsd:element name="MyObject">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="DisplayTitle"/>
<xsd:element ref="SubCollection" minOccurs='0' maxOccurs='1'/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>

At Level 2
<xsd:element name="MyObject">
<xsd:complexType>
<xsd:sequence>
<xsd:element ref="DisplayTitle"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>

This causes the parser to fail.

Suggestions please

Chennaikar