Why Reader.Value is Null?

Question

When I run this block of code with if clause(if (reader.Name == ControlID)),Reader.Value returns null,but when I omit the if clause it returns the right Value.
Have you got any idea why this happens?
            XmlTextReader reader = new System.Xml.XmlTextReader("D:\\k.xml");
            string contents = "";              
            while (reader.Read())
            {
                reader.MoveToContent();
                if (reader.Name == ControlID)               
                    contents = reader.Value;
            }