Unable to retrieve nodes using SelectSingleNode

[kavijaya]

Error message: "Unable to retrieve nodes using SelectSingleNode."
Can anyone tell me correct way of implementing this?
The following code always returns null:
(XML I am working with)

<?xml version="1.0" encoding="UTF-8"?>
<WdprAccountProfileResponse xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://Broadridge.com/Ascendis/Services/PhaseIV/Entities/">
  <Details i:nil="true" />
  <RawData>
    <ADP_MESSAGE Client_Number="0096" Message_id="WDPR/WDPR_ACCTPROFILES" Version="1.0" Session_Pool_id="mqpool096">
    <RESPONSE>
      <Turnaround/>
      <RequestReturn>N</RequestReturn>
      <Error_Response>
        <Error_Number>9022</Error_Number>
        <Error_Message>User not authorized for service</Error_Message>
      </Error_Response>
    </RESPONSE>
    </ADP_MESSAGE>
  </RawData>
  <StatusCode>SUCCESS</StatusCode>
  <AccountProfilesList>
    <AccountProfileEntity>
      <AccountName>TAIFOOK SECURITIES LIMITED</AccountName>
      <AddDate>03/29/2010</AddDate>
      <AdditionalInformation i:nil="true" />
  <ProfileNum>01</ProfileNum>
</AccountPortFolioEntity>

Here is the code I have return to retrieve node with profilenum='01':
(C# code)

 XmlDocument xdoc = new XmlDocument();
            xdoc.Load("C:\\Documents and Settings\\My Documents\\Visual Studio 2008\\Projects\\ConsoleApplication5\\WireProfile.xml");
 
            string profileno = "01";
            XmlNode root = xdoc.DocumentElement;
 
 
      XmlNode node = xdoc.SelectSingleNode("./AccountProfilesList[AccountProfileEntity/ProfileNum = '" + profileno + "']");
            Console.WriteLine(node["RecBankLocation"].InnerText);
            Console.WriteLine(node["ReceivingBankName"].InnerText);