why is this XML not validating?

Have the following XSD:

<?xml version="1.0"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://example.org/mytypes" xmlns:tns="http://example.org/mytypes">

<xsd:complexType name="personinfo2">
<xsd:sequence>
<xsd:element name="lastname" type="xsd:string"/>
</xsd:sequence>
</xsd:complexType>

<xsd:element name="employee" type="tns:personinfo2"/>

</xsd:schema>

and the following XML file:
<employee xmlns='http://example.org/mytypes'><lastname>smith</lastname></employee>


why is it failing validation with this message?:

"The element 'employee' in namespace 'http://example.org/mytypes' has invalid child element 'lastname' in namespace 'http://example.org/mytypes'. List of possible elements expected: 'lastname'."

this might not be an issue HERE, but check the fact that you're using single quotes instead of proper quotation marks in you XML file when you declare your namespace.