VB.NET Web Service that validates XML

[aliback9]

I am writing a web service that takes in an XML string that will then be validated with an XSD. I need some help, as this is my first web service and first try at validating xml with xsd. Here is my code, with some questions at the end.

Imports Microsoft.VisualBasic
Imports System.Xml
Imports System.Xml.Schema
 
Public Class DataValidator
    Const SCHEMA_SUFFIX As String = "XMLSchema.xsd"
    Const SCHEMA_NAMESP As String = "activationSchema"
 
    Private Failed As String
 
    Public Function ValidateXML(ByVal xmlData As String, ByVal custId As String) As String
        Failed = ""
        ' Create the XmlSchemaSet class.
        Dim sc As XmlSchemaSet = New XmlSchemaSet()
 
        ' Add the schema to the collection.
        sc.Add(SCHEMA_NAMESP, "http://localhost/ActivationData/" & custId & SCHEMA_SUFFIX)
 
        ' Create and load the XML document
        Dim doc As XmlDocument = New XmlDocument()
        doc.LoadXml(xmlData)
 
        ' Create an XmlNodeReader using the XML document
        Dim nodeReader As XmlNodeReader = New XmlNodeReader(doc)
 
        ' Set the validation settings.
        Dim settings As XmlReaderSettings = New XmlReaderSettings()
        settings.ValidationType = ValidationType.Schema
        settings.ValidationFlags = settings.ValidationFlags _
            Or XmlSchemaValidationFlags.ReportValidationWarnings Or XmlSchemaValidationFlags.AllowXmlAttributes
        settings.Schemas = sc
        AddHandler settings.ValidationEventHandler, AddressOf ValidationCallBack
 
        ' Create the XmlReader object.
        Dim reader As XmlReader = XmlReader.Create(nodeReader, settings)
 
        ' Parse the file. 
        While reader.Read()
        End While
 
        Return Failed
 
    End Function
 
 
    ' Compile a string of any validation errors
    Private Sub ValidationCallBack(ByVal sender As Object, ByVal e As ValidationEventArgs)
        Failed = Failed & "XML Validation Error: {0}" & e.Message & vbCrLf
    End Sub
 
End Class
 

My XSD, which resides at the root of the service:

<?xml version="1.0" encoding="utf-8"?>
<xsd:schema id="C10008XMLSchema"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns="activationSchema" elementFormDefault="qualified" targetNamespace="activationSchema">
<xsd:element name="activationData">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="custPO" type="xsd:string" minOccurs="1" />
<xsd:element name="itemCode" type="xsd:string" minOccurs="1" />
<xsd:element name="esn" type="xsd:string" minOccurs="1" />
<xsd:element name="npa" type="xsd:string" minOccurs="1" />
<xsd:element name="mdn" type="xsd:string" minOccurs="1" />
<xsd:element name="msid" type="xsd:string" minOccurs="1" />
<xsd:element name="activationCode" type="xsd:string" minOccurs="1" />
</xsd:sequence>
</xsd:complexType>
</xsd:element>
</xsd:schema>

My XML:
<activationData>
<custPO>1421</custPO>
<itemCode>C2125---C1819DGNI-00</itemCode>
<esn>03709911440</esn>
<npa>444</npa>
<mdn>mdn1212</mdn>
<msid>msid1212</msid>
<activationCode>650</activationCode>
</activationData>

When I pass the above xml into the service, I get this error:
"Could not find schema information for the element 'activationData'."

Questions:
1. The element exists in the xml - why the error?
2. In the cs.add statement, how can I get around having to hardcode the URL? Is this how you tell the process where the xsd is?
3. Am I even doing this right? Should I use the nodeReader?

Thank you!