How can I add a value to an form input field

How can I add a value to an form input field

Hello
 
I have this script where i call a jquery ajax to calclate something and then put it back in the form input so then i post everything to a php script where it insert it in mysql database.
 
Here is the script :
 
<!--Date/Time Picker -->
$(document).ready(function(){
 $("input#dep_d").AnyTime_picker(
  {format: "%Y-%c-%d", labelTitle: "Date"});
 $("input#c_off").AnyTime_picker(
  { format: "%H:%i", labelTitle: "Time",
        labelHour: "Hour", labelMinute: "Minute"});
 $("input#c_on").AnyTime_picker(
  { format: "%H:%i", labelTitle: "Time",
        labelHour: "Hour", labelMinute: "Minute"});
});
<!--Productivity calculation -->
$(document).ready(function(){
 
 $('input[name="capt"]').click(function()
 {
  var selected = $(this).val();
  var str = $("#prod").serialize();
  $.ajax({
   type: "POST",
   url: "prodcalc.php",
   data: str,
   success:
    function(data){
     $('input[name="pay1"]').val(data);
    }
  });
 });
});




























here is the form:
 
<form id="prod" name="prod" method="post" action="show-param.php">
        <table width="500" border="0" align="center" cellpadding="5" cellspacing="0">
    <tr>
           <th nowrap="nowrap">Departure Date</th>
            <th nowrap="nowrap">Chocks Off</th>
            <th nowrap="nowrap">Chcks On</th>
            <th nowrap="nowrap">TZD</th>
            <th nowrap="nowrap">Operating As</th>
          </tr>
          <tr>
            <td nowrap="nowrap">
                    <input name="dep_d" type="text" id="dep_d" value="yyyy-mm-dd" size="11"/>
            </td>
            <td nowrap="nowrap">       
           <input name="c_off" type="text" id="c_off" value="hh:mm" size="5" />
            </td>
            <td nowrap="nowrap">
           <input name="c_on" type="text" id="c_on" value="hh:mm" size="6" />
   </td>
            <td nowrap="nowrap">
          <select name="tzd" id="tzd">
            <option selected="selected">Please Select</option>
             <option value="0">GMT</option>
             <option value="1">GMT+1:00</option>
             <option value="2">GMT+2:00</option>
             <option value="3">GMT+3:00</option>
             <option value="3.5">GMT+3:30</option>
             <option value="4">GMT+4:00</option>
             <option value="5">GMT+5:00</option>
             <option value="5.5">GMT+5:30</option>
             <option value="6">GMT+6:00</option>
             <option value="7">GMT+7:00</option>
             <option value="8">GMT+8:00</option>
             <option value="9">GMT+9:00</option>
             <option value="9.5">GMT+9:30</option>
             <option value="10">GMT+10:00</option>
             <option value="11">GMT+11:00`</option>
             <option value="12">GMT+12</option>
             <option value="-1">GMT-1:00</option>
             <option value="-2">GMT-2:00</option>
             <option value="-3">GMT-3:00</option>
             <option value="-3.5">GMT-3:30</option>
             <option value="-4">GMT-4:00</option>
             <option value="-5">GMT-5:00</option>
             <option value="-6">GMT-6:00</option>
             <option value="-7">GMT-7:00</option>
             <option value="-8">GMT-8:00</option>
             <option value="-9">GMT-9:00</option>
             <option value="-10">GMT-10:00</option>
             <option value="-11">GMT-11:00</option>
             <option value="-12">GMT-12:00</option>
         </select>
  </td>
          <td nowrap="nowrap">
<div class="opr1">
              <input type="radio" name="capt" id="capt" value="capt" class="opr"/>Captain
              <input type="radio" name="capt" id="fo" value="fo" class="opr"/>First Officer
              </div>
              </td>
          </tr>
          <tr align="center">
   <td nowrap="nowrap">Productivity</td>
            <td colspan="4" align="left" nowrap="nowrap">
   <input name="pay1" type="text" disabled="disabled" class="disabledInput" id="pay1" />
<!--         <span id="pay1">0.000 KD</span>   <input name="pay1" type="text" disabled="disabled" class="disabledInput" id="pay1" value=""/>-->
<input type="submit" name="submit" id="submit" value="Submit" /></td>
          </tr>
        </table>
</form>




































































 
Although it shows the value in the input boxin IE but the value itself is not carried to the show-param.php script.
 
Please any help is highly appreciated.