this is not the same as a checkbox group.
Server validations cannot be used to validate checkboxes used in a multiple insert behavior like this.
the problem is that the checkboxes are dynamically named.
to work around this, add the following hidden form element just before the submit button:
<input name="checkCount" type="hidden" id="checkCount" value="<?php echo $RepeatSelectionCounter_1; ?>" />
and add this code at line 1:
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$checked=0;
$iterations = isset($_POST['checkCount'])?$_POST['checkCount']:0;
for($i=0; $i<=$_POST['checkCount'];$i++) {
if(isset($_POST['CheckboxGroup1_'.$i]) && $_POST['CheckboxGroup1_'.$i] != "") $checked++;
}
}
?>
then use numeric validation. set the server variable to:
$checked
set the minimum number to 1 and the maximum to 10000