QuickForm - advcheckbox and check_all

Hi everybody ! I created a Form with Quick Form and now I would be glad to set a link which enables to check all the advcheckbox I set. I try with javascript but it doesn't works... I have no idea how to do that through PHP (I use PEAR::Pager inside my Form too). Here is the code I use to set up the form : $form->addElement('link', 'select_all', '', '', '<img src="./check.png" border=0 alt="Select All" title="Select All">', array ('onclick' => "javascript:check_all(this.form);") ); Here is the javascript I pu in the HEAD section : <script type="text/javascript"> function check_all(dataForm) { for (i=0; i < dataForm.elements.length; i++) { if (dataForm.elements[i].type == 'checkbox') { dataForm.elements[i].checked = true; } } } </script> Is anybody have a suggestion to perform such a feature ?(I would be glad to use PPHP and PEAR classes, but all I try does't work too... Best regards Mos