Form logic works in Chrome, not in IE

Question

I have a basic HTML form with a input field that I want to start disabled but change to enabled based on a previous select input. This works in Chrome but fails in IE... probably something stupidly easy but I cannot find a solution..

<script language="javascript">
function enableFeedback(val)
{
    if(val == "Feedback"){
    document.frmQuestionnaire.txtAns3.disabled=false;
}
else {
    document.frmQuestionnaire.txtAns3.value="";
    document.frmQuestionnaire.txtAns3.disabled=true;

}
}
</script>

<td valign="top" colspan="3"><select name="select" onChange="enableFeedback(this.value)">
            <option>Select an option...</option>
            <option>Feedback</option>
            <option>No feedback</option>
    </select></td>
   </tr>
   <tr>
    <td valign="top" align="left" width="92" bgcolor="#ffffff"><font size="2" face="Arial, Helvetica, sans-serif">Comments:</font></td>
    <td valign="top" colspan="3"><input name="txtAns3" size="6" disabled="disabled"></td>

Answer 1

<script language="javascript">
function updateFeedback(val)
{
val=+val;
var txtElem = document.getElementById("txtAns3");
txtElem.disabled=val?"":"disabled";
val||(txtElem.value="");
}
</script>

<td valign="top" colspan="3">
<select name="select" onChange="updateFeedback(this.options[this.selectedIndex].value)">
            <option value="0">Select an option...</option>
            <option value="1">Feedback</option>
            <option value="0">No feedback</option>
    </select></td>
   </tr>
   <tr>
    <td valign="top" align="left" width="92" bgcolor="#ffffff"><font size="2" face="Arial, Helvetica, sans-serif">Comments:</font></td>
    <td valign="top" colspan="3">
    <input id="txtAns3" name="txtAns3" size="6" disabled></td>