Form - dropdown valg udløser et aktivt felt?

<form>
<select name="drik" onchange="checkSelect(this)">
<option value="smirnoff">Smirnoff vodka</option>
<option value="tuborg">Tuborg 33cl pilsner el. lign</option>
<option value="gajol">Gajol</option>
<option value="pernod">Pernod</option>
<option value="cuba">Cuba (strawberry, caramel, eller lign.)</option>
<option name="andet" value="andet">&nbsp; &nbsp; &nbsp *Anden - angiv alkoholprocent til højre</i></option>

</select>

&nbsp; &nbsp * <input type="text" name="andenprocent" id="andenproducent" value="" size="2" disabled>size="2" disabled>

</form>

<script type="text/javascript">
    function checkSelect(ele){
        document.getElementById('andenproducent').disabled = ele[ele.selectedIndex].value == "andet" ? false : true
    }
</script>

Det var bare select der skulle have en value.. Spg lukket