I can't edit the text with PhpNuke

Hello,
In the add.php of module Journal I have replaced a textarea with FCKeditor:

$oFCKeditor = new FCKeditor('bodytext');
$oFCKeditor->BasePath = '/FCKeditor/';
$oFCKeditor->Width = '600' ;
$oFCKeditor->Height = '300' ;
$oFCKeditor->Value = 'Digitare testo...';
$oFCKeditor->Create();

This is ok for add a new text.
But in the other file modify.php which is the line of code for change the previous text?

Thanks

(sorry. I'm italian and speak very bad your lang)