Internet Explorer 9 not posting AJAX post request

My javascript AJAX code is below. This works as expected in Chrome and FF, but in IE, I've discovered the POST variables never make it to customer_savedesign.php below, yet it still gives output "got result" in the console. I thought IE will work if we use the jquery .serialize() function on form data, but it's still not working. I'm also not using .submit(), just directly making an ajax call.

 $.ajax({
           type: "POST",
           url: "customer_savedesign.php",
           data: $('#designform').serialize(), 
           success: function(data)
          {   arr = data.split(':');
              console.log("got result");
              // show response from the php script.
              console.log("arr1 is " + arr[1]);
           } 
       });

Edit

My form looks like this:

    <div class='lefttable'>
    <form id='designform' name='designform' method='post' action='customer_savedesign.php'> 
<table style='margin-top:20px;text-align:right; bidi-direction:rtl; font-size:12pt' class='form' id='arabic-fields'>

<tr><td>اسم الشركة</td></tr>
<tr><td> <textarea tabindex="1" type='text' class='large ar arindic expand20-60' id='ar_Company_Name' style='bidi-direction:rtl; text-align:right;'></textarea> </td></tr>

<tr><td>رسالة الشركة</td></tr>
<tr><td> <textarea type='text' tabindex="1" class='large ar arindic expand20-60' id='ar_Company_Message' style='bidi-direction:rtl; text-align:right;'></textarea> </td></tr>

</table>
<input type='button' id='newfield' class='ar newfield' value='نص جديد' />

<input type='hidden' id='state_history' style='width:300px; height:30px;' />
<input type='hidden' id='current_state' style='width:300px; height:30px;' />
<input type='hidden' name='designid' id='designid' value='<?php echo $d->getID(); ?>' />
<input type='hidden' name='parentid' id='parentid' value='<?php echo $d->getParentID(); ?>'/>
<input type='hidden' name='productid' id='productid' value='0'/>
<input type='hidden' name='templateid' id='templateid' value='0'/>
<input type='hidden' name='orientation' id ='orientation' value='<?php echo $orientation; ?>' />
<input type='hidden' name='side' id='side' value='<?php echo $side; ?>' />
<input type='hidden' name='userid' id='userid' value='<?php echo $user_id; ?>'/>
<input type='hidden' name='usertype' id='usertype' value='<?php echo $user_type; ?>'/>
<input type='hidden' name='designdata' id='designdata' />
<input type='hidden' name='designtag' id='designtag' />
<input type='hidden' name='orderdetailid' id='orderdetailid' value='<?php echo $order_detail_id; ?>' />
<input type='hidden' name='wasnew' id='wasnew' value='<?php echo $wasnew; ?>' />
<input type='hidden' name='action' id='action' value='<?php echo $_GET['action']; ?>' />
<input type='hidden' name='saveasaction' id='saveasaction'  />
</form>
</div>

try using .serializaArray() instead of .serialize(). Also, do not use console.log() in IE since it will fail if the console is not open.