Quickform ElementGrid - how to addRule()

I am adding a grid of editable 'text' elements to a ElementGrid in HTML_Quickform. I would like to add validation rules ... In the code below (***) I try and use "addRule" to no avail. Any ideas on how to make the validation of each element work? Thanks. { $elementGrid =& $form->addElement('elementGrid', 'elementGrid', $prompt, array('actAsGroup' => true)); foreach($colheadings as $aheading) { $elementGrid->addColumnName($aheading); } $numrows = count($data); // data contains 2 dimenensional array of

numbers                                                                                                                                                                

$numcols = count($colheadings); // echo "addGrid:: numrows=$numrows numcols=$numcols

<br>";                                                                                                                                                                               

for ($i=0; $i<$numrows; $i++) { $row = null; for($j=0; $j<$numcols; $j++) {

     $itemname = "grid_${name}_${i}_${j}";
     $row[] =& HTML_QuickForm::createElement('text', $itemname,   $itemname,  array('size' => 10));
***      $form->addRule($itemname,  "field must be numeric", 'numeric',  null, 'server');

} $gridrows[] = $row; } $elementGrid->setRows($gridrows); }