I'm getting close to solve this, but I'm getting an error in the following code:

Code:
dim ns as string = "http://schemas.microsoft.com/office/2009/07/customui"
dim xsdschema as string = mypathtoxsdschema

Dim x As New XmlDocument
x.LoadXml(myxml)
x.Schemas.Add(ns, xsdschema)
myxml:
Code:
customUI xmlns="http://schemas.microsoft.com/office/2009/07/customui">
   <ribbon startFromScratch="false">
      <tabs>
         <tab id="customTab" label="Custom Tab">
            <group id="customGroup" label="Custom Group">
               <button id="customButton" label="Custom Button" imageMso="HappyFace" size="large" onAction="Callback" />
            </group>
         </tab>
      </tabs>
   </ribbon>
</customUI>
ERROR: x.Schemas.Add(ns, xsdschema): The root element of a W3C XML Schema should be <schema> and its namespace should be 'http://www.w3.org/2001/XMLSchema'.