XmlNodeList is empty with NameSpace in C# code

Question

I want go into a specific path '/trace/calls/call/userTableParameters/parameter' and take out all parameter names with values. I have used a namespace in xpath while doing xmlnode selection. It returns the right fisrt childnode 'parameter'. but xmlnodelist doesn't return any content further. What would be the problem in my code?

 XmlDocument doc = new XmlDocument();
    doc.Load(@"d:\Drops.xml");

    XmlNamespaceManager nsmgr = new XmlNamespaceManager(doc.NameTable);
    nsmgr.AddNamespace("nsTrace", "http://www.polystar.com/OSIX/monitoring/traceSchemaV1.0");
    XmlNode ParameterNode = doc.SelectSingleNode("//nsTrace:userTableParameters", nsmgr);
    XmlNodeList ParameterNodeList = ParameterNode.SelectNodes("//parameter");

    foreach (XmlNode node in ParameterNodeList)
            {
                Parameter drop = new Parameter();
                drop.name = node.Attributes.GetNamedItem("name").Value;
                drop.content = node.InnerText;

                callParameter.ParameterList.Add(drop);
            }


    <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<trace xmlns="http://www.polystar.com/OSIX/monitoring/traceSchemaV1.0">
    <calls>
        <call>
            <messages>
                <message>
                    <parameters>
                        <parameter name="Timestamp">Wed 11 Nov 2015 11:58:14.096</parameter>
                        <parameter name="Direction">---&gt;</parameter>
                        <parameter name="Resulting Status">Normal</parameter>
                        <parameter name="Resulting State Name">AP Request Pending</parameter>
                        <parameter name="Source Address">11.111.111.11</parameter>
                        <parameter name="Dest Address">11.222.222.22; ABC2</parameter>
                        <parameter name="Media Probe Id"/>
                        <parameter name="Deciphered"/>
                    </parameters>
                </message>  
            </messages>
            <userTableParameters>
                <parameter name="Start Time">11:58:14.096</parameter>
                <parameter name="End Time">11:58:27.191</parameter>
                <parameter name="Duration">00:00:13.095</parameter>
                <parameter name="Date">Wed 11 Nov 2015</parameter>
                <parameter name="Protocol">AP</parameter>
                <parameter name="Status">End</parameter>
                <parameter name="AP II"/>
                <parameter name="AP TI">e0a5e84d'H</parameter>
                <parameter name="AP Cause">3; due-to-generated-reason</parameter>
            </userTableParameters>
        </call>
    </calls>
</trace>

Answer 1

Your Xpath query is wrong. I also shorten your code. More information about Xpath

XmlNamespaceManager nsmgr = new XmlNamespaceManager(doc.NameTable);
nsmgr.AddNamespace("nsTrace","http://www.polystar.com/OSIX/monitoring/traceSchemaV1.0");
XmlNodeList ParameterNodeList = doc.SelectNodes("//nsTrace:userTableParameters//nsTrace:parameter", nsmgr);