read a xml file with namespace

Hi,

I just try to read an exported OfficeUI file (Word.exportedUI):

$MSNamespace= @{mso=http://schemas.microsoft.com/office/2009/07/customui}

select-Xml -Path $XMLFile -XPath "//mso:cmd" -Namespace $MSNamespace

The error I got is: the content of the XML file could not be converted into System.Xml.XmlDocument.

What is wrong?