My xml won't validate against my schema - xsd

Question

I have just made my first attempt at XSD.
When I try and validate my XML against my XSD, I get the error:
Cannot find the declaration of element 'linkage'.
Below I give my XSD and a cut down version of my XML. I've tried adding a namespace qualifier to the top element in my XML and also to every element (changing the XSD to qualified) and it did not help. I'm obviously making a basic mistake. As I'm new to XSD, if you could include what I need to change in my XML and/or XSD I would be very grateful.
XSD:
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema
xmlns:xs="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://www.stephenwaring.me.uk/android/nestedsettings"
xmlns="http://www.stephenwaring.me.uk/android/nestedsettings"
elementFormDefault="unqualified">
<xs:element name="linkage">
<xs:complexType>
<xs:sequence>
<xs:element name="preference-screen" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="parent" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="child" maxOccurs="unbounded">
<xs:complexType>
<xs:attribute name="key" type="xs:token" use="required" />
<xs:attribute name="reformat" type="xs:boolean" />
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attributeGroup ref="keyed" />
<xs:attribute name="preference-screen" type="xs:token" use="required" />
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attributeGroup ref="keyed"/>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attributeGroup ref="defaults"/>
</xs:complexType>
</xs:element>
<xs:attributeGroup name="defaults">
<xs:attribute name="html" type="xs:boolean" />
<xs:attribute name="prefix" type="xs:string" />
<xs:attribute name="suffix" type="xs:string" />
<xs:attribute name="separator" type="xs:string"/>
<xs:attribute name="reformat" type="xs:boolean" />
<xs:attribute name="shaddow" type="xs:boolean" />
<xs:attribute name="child-summary" type="xs:boolean" />
<xs:attribute name="shadow-separator" type="xs:string"/>
</xs:attributeGroup>
<xs:attributeGroup name="keyed">
<xs:attributeGroup ref="defaults" />
<xs:attribute name="key" type="xs:token" use="required" />
</xs:attributeGroup>
</xs:schema>
Cut down XML:
<?xml version="1.0" encoding="UTF-8"?>
<linkage
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://stevewaring.me.uk/android/nestedsettings nestedsettings.xsd"
xmlns="http://www.stevewaring.me.uk">
<preference-screen
key="preferences1">
<parent
key="prefFruit"
preference-screen="preferences2">
<child key="prefFruit1"/>
<child key="prefFruit2"/>
</parent>
</preference-screen>
</linkage>

Answer 1

Your XSD defines elements in http://www.stephenwaring.me.uk/android/nestedsettings whereas your document element is in http://www.stevewaring.me.uk. Make them to agree, one way or the other, and it should take care of the error you're having.
I've added a fixed XML, there's another issue related to use of unqualified elements.
<?xml version="1.0" encoding="UTF-8"?>
<linkage xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.stephenwaring.me.uk/android/nestedsettings nestedsettings.xsd" xmlns="http://www.stephenwaring.me.uk/android/nestedsettings">
<preference-screen xmlns="" key="preferences1">
<parent key="prefFruit" preference-screen="preferences2">
<child key="prefFruit1"/>
<child key="prefFruit2"/>
</parent>
</preference-screen>
</linkage>