Can't get attribute value with C# XPath

I've spent so much time with this already, still can't get the value of NTE attribute :(. Can someone please help?

C#

        StreamReader sr = new StreamReader(resp.GetResponseStream());
        XPathDocument xmlDoc = new XPathDocument(sr); // holds xml document
        XPathNavigator xmlNav = xmlDoc.CreateNavigator(); //evaluates XPath expressions
        XPathNodeIterator node = xmlNav.Select("/DATA2SC/CALL");
        string dne = xmlNav.GetAttribute("NTE", "");

        Console.WriteLine(dne);
        sr.Close();

XML:

<?xml version="1.0"?>
<DATA2SC PIN="00000">
    <CALL
    TR_NUM="00000001"
    STATUS="WAITING_FOR_APPROVAL"
    NTE="$15.00">
        <PROBLEM>
            Text
        </PROBLEM>
    </CALL>
</DATA2SC>