XML : Get node from XmlDocument using xpath

I have an XML document

  <?xml version="1.0"?>     <xmlTicket>       <TicketDataSet xmlns="http://tempuri.org/TicketDataSet.xsd">         <TICKET>           <One_Call_Center>UFPO</One_Call_Center>           <Ticket_Number>03192-000-001</Ticket_Number>           <Version_Number>0</Version_Number>           <Ticket_Type>Regular</Ticket_Type>           <Primary_CDC>    

(the rest is removed for brevity)

Using xmlspy, i pulled the xpath

/xmlTicket/TicketDataSet/TICKET/Ticket_Number

now when i try to grab the node in C#

    XmlNode node = xmlTicket.DocumentElement.SelectSingleNode("/xmlTicket/TicketDataSet/TICKET/Ticket_Number");      string nodeval = node.InnerText;    

node is null.

The only time i get a non-null value is when i bring the xpath down to xmlTicket

Am I missing something to get the value of Ticket_Number