Changing ToolbarSet

I edited fckconfig.js in /FCKeditor (ToobarSet Basic). I added 'underline' after italic and saved the file.

My construction of the editor, I have the following code:

$oFCKeditor = new FCKeditor('description') ;
$oFCKeditor->BasePath = 'FCKeditor/';
$oFCKeditor->Value = $description;
$oFCKeditor->ToolbarSet = 'Basic';

$oFCKeditor->Create() ;

It uses the "Basic" ToolbarSet, but it doesn't have underline on the toolbar. What have I done wrong?
---Michael