I was trying to add a validation for an Empty Field. If field is empty, form will not be submitted. But my "required" attributes not working.
Birthdate: 
<select name="month" required>
<option value="0" required>Select Month</option>
    <?php
        for( $m = 1; $m <= 12; $m++ )
            {
                $num = str_pad( $m, 2, 0, STR_PAD_LEFT );
                $month = date( 'F', mktime( 0, 0, 0, $m + 1, 0, 0 ) );?>
                <option value="<?php echo $num;?>"><?php echo $month; ?></option>
                <?php
            }
    ?>
    </select>
</select>
 
     
     
    