If I understand you correctly your checkbox is not submitting with the form?
If that is the case, I had a fun time with this question on this thread HERE
PHP wants you to check to see if a checkbox is set or not by verifying whether or not there is a corresponding element in the POST array. If the checkbox was checked, there will be an element of the same name in the POST array (that element will have a NULL value), if the checkbox was NOT checked, then there will be NO matching element in the POST array.
The code would look something like this:
Your input element remains the same --
<input name="checkall" type="checkbox" value="ON" <?php echo set_checkbox('checkall', 'ON'); ?> />
Postback Handler Page gets a new way to validate a checkbox --
if(isset($_POST["checkall"])
{
$checkall = TRUE;
}
else
{
$checkall = FALSE;
}
Hopefully I helped, its late and your question is sparse on details.
Regards