Class 'FCKeditor' not found

<?php include("fckeditor/fckeditor.php"); ?>

<?php
$oFCKeditor = new FCKeditor('contenu');
$oFCKeditor->Config["CustomConfigurationsPath"] = 'fckconfig_graphinet.js';
$oFCKeditor->BasePath = 'fckeditor/';
$oFCKeditor->Value = $contenu;
$oFCKeditor->Width = '453' ;
$oFCKeditor->Height = '400' ;
$oFCKeditor->Create();
?>