PHP: why is my form not transferring data through $_POST?

I want the id, weekday, month, month-day, time, time zone, year, inside local IP, and inside global IP to be submitted by the form and end up in $_POST. However, the time zone isn't working, and I don't know why. The time zone is being controlled by the SELECT element, and the name of each tag is 'tz'.

Here is the code to the form in the view:

<form action='/mysecureview/admin_view/log_index.php' method='post'>
        <ul>
            <input type='hidden' value='<?php echo $id; ?>' name='id'>
            <li><label>weekday</label><input <?php echo (($weekday_error == TRUE)?"id='weekday_error'":'')?> type='text'    value='<?php echo $wd; ?>'   name='wd'></li>
            <li><label>month</label><input <?php echo (($month_error == TRUE)?"id='month_error'":'')?> type='text'      value='<?php echo $m; ?>'     name='m'></li>
            <li><label>month-day</label><input <?php echo (($month_day_error == TRUE)?"id='month_day_error'":'')?> type='text'  value='<?php echo $md; ?>'   name='md'></li>
            <li><label>time</label><input <?php echo (($time_error == TRUE)?"id='time_error'":'') ?> type='text'       value='<?php echo $t; ?>'    name='t'></li>
            <select>
                <option value="0">Please, select timezone</option>
                <?php 
                foreach(tz_list() as $t) { ?>

                <option value="<?php print $t['zone']?>"<?php echo "name='tz'";?> >
                    <?php print $t['diff_from_GMT'] . ' - ' . $t['zone'] . ' '; 
                    ?>
                </option>
                <?php } ?>
            </select>

            <li><label>year</label><input <?php echo (($year_error == TRUE)?"id='year_error'":'') ?> type='text'       value='<?php echo $y; ?>'    name='y'></li>
            <li><label>inside local IP address</label><input <?php echo (($ilp_error == TRUE)?"id='ilp_error'":'') ?> type='text' value='<?php echo $ilp ?>' name='ilp'></li>
            <li><label>inside global IP address</label><input <?php echo (($igp_error == TRUE)?"id='igp_error'":'') ?> type='text' value='<?php echo $igp ?>' name='igp'></li>

            <li><input type='submit' value='submit' name='show'></li>
            <input type='hidden' value='update-log' name='action'>
        </ul>
    </form>

In the controller, I use var_dump($_POST); to get the following output:

array(10) {
["id"] "3"
["wd"] "Mon"
["m"] "Mar"
["md"] "4"
["t"] "15:01:43"
["y"] "2015"
["ilp"] "10.18.149.220"
["igp"] "127.221.137.254"
["show"] "submit"
["action"] "update-log"
}

Why is PHP not sending the time zone through $_POST['tz']?