I am trying to load an exisiting xml file and append a
node to it then save the xml file but the save method
fails.  Here is the code:

IXMLDOMNode n;
n = thisXDocument.DOM.selectSingleNode
        ("my:root/wns:section");

object loadFilePath = "d:\\xml\\.xml";
IXMLDOMDocument newDOM = thisXDocument.CreateDOM();
newDOM.load(loadFilePath);

IXMLDOMNode no = newDOM.selectSingleNode
       ("base/Section");
               
no.appendChild(n);
newDOM.save(loadFilePath);

The error is:
System.UnauthorizedAccessException
Access is denied.

I granted full control to Everyone to the folder and the
file but I am still getting this error.  Am I missing
something simple?