PHP: Cannot instantiate non-existent class

<?php
include_once("/Test/AdminTool/FCKEditor/fckeditor.php");
?>


       <?php
      This is line 103------>$oFCKeditor = new FCKeditor('PageEdit') ;
         $oFCKeditor->BasePath = '/FCKEditor/' ;
         $oFCKeditor->Value = '<p>This is some <strong>sample text</strong>. You are using <a href="http://www.fckeditor.net/">FCKeditor</a>.</p>' ;
         $oFCKeditor->Create() ;
      ?>