Novice XSD namespace question

[rss181919]

I have an xsd I am trying to link up to an xml so the xml content will be validated (see below). I am having trouble with namespaces. If you attempt to validate as is, it fails stating on the brushes element and the only way I can get it to work is to undeclare the default namespace on the xml root element. So I think I have a namespace conflict between the brushes element in the xsd and the brushes element in the xml. Can't figure out why that is. Any explanation is much appreciated.

<?xml version="1.0" encoding="utf-8" ?>
<xs:schema xmlns:xs="

http://www.w3.org/2001/XMLSchema"

targetNamespace="mynamespace">
<xs:element name="root">
<xs:complexType>
<xs:sequence>
<xs:element name="brushes">
<xs:complexType>
<xs:sequence>
<xs:element name="brush" minOccurs="0" maxOccurs="unbounded">
<xs:complexType>
<xs:attribute name="id" type="xs:string" use="required"></xs:attribute>
<xs:attribute name="type" use="required">
<xs:simpleType>
<xs:restriction base="xs:string">
<xsattern value="image|video"></xsattern>
</xs:restriction>
</xs:simpleType>
</xs:attribute>
<xs:attribute name="uri" type="xs:string"></xs:attribute>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="theme_references">
<xs:complexType>
<xs:sequence>
<xs:element name="theme_reference" minOccurs="0" maxOccurs="unbounded">
<xs:complexType>
<xs:attribute name="id" type="xs:string" use="required"></xs:attribute>
<xs:attribute name="icon_brush" type="xs:string" use="required"></xs:attribute>
<xs:attribute name="theme_uri" type="xs:string" use="required"></xs:attribute>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>


<?xml version="1.0" encoding="utf-8"?>
<root xmlns="mynamespace"
xmlns:xsi="

http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="mynamespace theme_references.xsd">
<brushes>
<brush id="alphabet_icon" type="image" uri="content\themes\alphabet\images\A.png"></brush>
</brushes>
<theme_references>
<theme_reference id="alphabet" icon_brush="alphabet_icon" theme_uri="content\themes\alphabet\alphabet.xml"></theme_reference>
</theme_references>
</root>