Opstelling-script werkt wel in FF niet in IE

<?php
    include 'header.php';
    $sOpstelling = $formation;

    $aOpstelling = explode('-',$sOpstelling);

    if (isset($_POST['verander'])) {
        $sQuery1 = 'UPDATE players SET basisposition="W" WHERE teamID=' . $teamid. ' AND basisposition="K"';
        $sQuery2 = 'UPDATE players SET basisposition="K" WHERE teamID=' . $teamid. ' AND name="' . $_POST['K'] . '"';
        $iResult1 = mysql_query($sQuery1);
        $iResult2 = mysql_query($sQuery2);

        $aPositie = array('V', 'M', 'A');
        for ($i = 0; $i < 3; $i ++) {
            for($ii = 1; $ii < $aOpstelling[$i]+1; $ii ++) {
                $sPos = $aPositie[$i] . $ii;
                $sQuery3 = 'UPDATE players SET basisposition="W" WHERE teamID=' . $teamid. ' AND basisposition="' . $sPos . '"';
                $sQuery4 = 'UPDATE players SET basisposition="' . $sPos . '" WHERE teamID=' . $teamid. ' AND name="' . $_POST[$sPos] . '"';
                $iResult3 = mysql_query($sQuery3);
                $iResult4 = mysql_query($sQuery4);
            }
        }
    }

    $sQuery = 'SELECT * FROM players WHERE teamID=' . $teamid. '';
    $iResult = mysql_query($sQuery);
    $aSpelers = array();
    $i = 1;
    while($aObject = mysql_fetch_object($iResult)) {
        $aSpelers[$i][$aObject->position][$aObject->basisposition] = $aObject->name;
        $i ++;
    }

    function set_selectbox ($id, $options) {
        echo PHP_EOL . '<select id="' . $id . '" name="' . $id . '">';
        echo PHP_EOL . '<option value="0" selected>&#60;Geen&#62;</option>';
        echo PHP_EOL . '<optgroup label="Aanvallers">';
        foreach ($options as $key => $value) {
            foreach ($options[$key] as $key2 => $value2) {
                foreach($options[$key][$key2] as $key3 => $value3) {
                    echo PHP_EOL;
                    if ($key2 == "A" && $key3 == $id) echo '<option value="' . $value3 . '" selected>' . $value3 . '</option>';
                    elseif ($key2 == "A") echo '<option value="' . $value3 . '">' . $value3 . '</option>';
                }
            }
        }
        echo PHP_EOL . '</optgroup><optgroup label="Middenvelders">';
        foreach ($options as $key => $value) {
            foreach ($options[$key] as $key2 => $value2) {
                foreach($options[$key][$key2] as $key3 => $value3) {
                    echo PHP_EOL;
                    if ($key2 == "M" && $key3 == $id) echo '<option value="' . $value3 . '" selected>' . $value3 . '</option>';
                    elseif ($key2 == "M") echo '<option value="' . $value3 . '">' . $value3 . '</option>';
                }
            }
        }
        echo PHP_EOL . '</optgroup><optgroup label="Verdedigers">';
        foreach ($options as $key => $value) {
            foreach ($options[$key] as $key2 => $value2) {
                foreach($options[$key][$key2] as $key3 => $value3) {
                    echo PHP_EOL;
                    if ($key2 == "V" && $key3 == $id) echo '<option value="' . $value3 . '" selected>' . $value3 . '</option>';
                    elseif ($key2 == "V") echo '<option value="' . $value3 . '">' . $value3 . '</option>';
                }
            }
        }
        echo PHP_EOL . '</optgroup><optgroup label="Keepers">';
        foreach ($options as $key => $value) {
            foreach ($options[$key] as $key2 => $value2) {
                foreach($options[$key][$key2] as $key3 => $value3) {
                    echo PHP_EOL;
                    if ($key2 == "K" && $key3 == $id) echo '<option value="' . $value3 . '" selected>' . $value3 . '</option>';
                    elseif ($key2 == "K") echo '<option value="' . $value3 . '">' . $value3 . '</option>';
                }
            }
        }
        echo PHP_EOL . '</optgroup></select>';
    }
?>
<script type="text/javascript" src="mootools.js"></script>
<script type="text/javascript">
    window.addEvent ('domready', function () {
        $$('form#opstelling select').each (function (item) {
            item.addEvent ('change', function () {
                check_other_players (this);
            });
        });
    });
    function check_other_players (select_to_check) {
        $$('form#opstelling select').each (function (item) {
            if (item.id != select_to_check.id && item.value == select_to_check.value) {
                item.value = 0;
            }
        });
    }
</script>
<style type="text/css">
div#opstelling {
  background: url("plaatjes/veld.png") no-repeat;
  text-align: center;
}

</style>
<?php
echo '<div id="opstelling">';
echo '<form id="opstelling" method="post" action="test.php">';
echo '<br /><br />';
echo '<font color="white"><b>Keeper:</b></font><br />';
set_selectbox('K', $aSpelers);
echo '<br /><br />';
echo '<font color="white"><b>Verdediging:</b></font><br />';
for($i = 1; $i <= $aOpstelling[0]; $i++){
    set_selectbox('V'.$i,$aSpelers);
}
echo '<br /><br />';
echo '<font color="white"><b>Middenveld:</b></font><br />';
for($i = 1; $i <= $aOpstelling[1]; $i++){
    set_selectbox('M'.$i,$aSpelers);
}
echo '<br /><br />';
echo '<font color="white"><b>Aanval:</b></font><br />';;
for($i = 1; $i <= $aOpstelling[2]; $i++){
    set_selectbox('A'.$i,$aSpelers);
}
echo '<br /><br /><br /><br />';
echo '</div>';
echo '<br />';
echo '<center><input type="submit" value="Verander" name="verander"></center>';
echo '</form>';

include 'bottom.php';
?>