XML : Select Single Node Value from XML using F#

I have a very simple xml file:

  <?xml version="1.0" encoding="utf-8"?>  <package xmlns="http://schemas.microsoft.com/packaging/2010/07/nuspec.xsd">      <metadata>          <id>SomeSoftware</id>          <title>Some Software</title>          <version>1.2.3</version>      </metadata>  </package>    

From this file I would like to extract the value of the version node, using F#.

  let xmlDocument = new XmlDocument()  let namespaces = new XmlNamespaceManager(xmlDocument.NameTable);  namespaces.AddNamespace("ns", "http://schemas.microsoft.com/packaging/2010/07/nuspec.xsd");  xmlDocument.Load "software.nuspec"    let node = xmlDocument.SelectSingleNode "/package/metadata/version" :?> XmlElement  if node = null then    printfn "unable to find version"  else    printfn "%s" node.Value    

I have tried a few variations on this, but I don't seem to be able to print the version to my console.