XmlDocument获取指定节点属性

[wpxxsyzx]

Sub Main()
Dim doc As XmlDocument = New XmlDocument()
doc.Load("customUI14.xml")
For Each att As XmlAttribute In doc.SelectSingleNode("customUI").Attributes
Console.WriteLine(att.Name)
Next
End Sub
为何总是提示System.NullReferenceException:“未将对象引用设置到对象的实例。”




customUI14.xml文件内容如下
<customUI xmlns="http://schemas.microsoft.com/office/2009/07/customui">
<ribbon>
<tabs>
<tab id="MyTab" label="示例03" insertBeforeMso="TabHome">
<group id="Group1" label="示例组">
<button id="Button1" label="按钮1 " size="large" image="er"/>
<button id="Button2" label="按钮2 " size="large"
image="we" />
</group>
</tab>
</tabs>
</ribbon>
</customUI>

[stherix]

<customUI xmlns="http://schemas.microsoft.com/office/2009/07/customui">
有命名空间的xml文件,在解析的时候也需要把命名空间加上，才能解析到。做法如下：

System.Xml.XmlNamespaceManager nsmgr = new System.Xml.XmlNamespaceManager(doc.NameTable);
nsmgr.AddNamespace("ns", "http://schemas.microsoft.com/office/2009/07/customui");
System.Xml.XmlNode root = doc.SelectSingleNode("ns:customUI", nsmgr);

[wpxxsyzx]

还是报错啊！