$("tr#r26").addclass is not a function error

$("tr#r26").addclass is not a function error

using this script:

  1.         <script src="http://code.jquery.com/jquery-latest.min.js"></script>
            <script type="text/javascript">
            function Antwoord(id,vraagnummer,antwoord)    {
                alert("Je klikte op id = "+id+" van vraagnummer " + vraagnummer + " antwoord " +antwoord);
            }
            function GreyOutRows() { 
            /* '.$jquery.' */
            $("tr#r26").addclass("hidden");     
            }
           
            $(document).ready(function () {
            GreyOutRows();
            });

            </script>