[jQuery] link stops working in fragment returned from ajax depending on select

[K Bouton]

I have two dropdown boxes, which, when clicked, return via ajax some
information in a div.  Inside that information is are multiple links.

When I click on the left select- the links in the div below work fine.
If I refresh and click on the right select- the links in the div below
work fine.
So each individual select box works as I would expect it.

But...
if I refresh and click on the left select, then click on the right
select - the link for that right select work fine but the links from
the left select no longer work?

The links for the right select always work, regardless

See http://ncas-cms.nerc.ac.uk/data/startFiles/not_working_anim_overlay.php

Any ideas what is going wrong?

abbreviated code below for the form - hand typed in so there may be
typos

[code]
    $(document).ready(function() {
    $("#wrapBA").hide();
    $("#wrapMO)").hide();
      $("select#ba").change(function() {
        var ba = $("select#ba").val();
        //var ba = $
(this).children("option:selected").attr("value");
          $.ajax({
            type: "POST",
            url: "not_working_overlay_info.php",
            data: "ba=" + ba,
            dataType: "html",
            cache: false,
            error: function(){
              alert('Error loading BA start files');
            },
            success: function(data) {
              $("#wrapBA").html(data);
              $("#BAModelName").html("BA -
"+ba).show().addClass("BAModelName");
              $("#wrapBA").slideDown('slow');
              }
            });
             return false;
      });
      $("select#mo").change(function() {
        var mo = $("select#mo").val();
          $.ajax({
            type: "POST",
            url: "not_working_overlay_info.php",
            data: "mo=" + mo,
            dataType: "html",
            cache: false,
            error: function(){
              alert('Error loading MO start files');
            },
            success: function(data) {
              $("#wrapMO").html(data);
              $("#MO_ModelName").html("MO -
"+mo).show().addClass("MO_ModelName");
              $("#wrapMO").slideDown('slow');
              }
            });
             return false;
      });
});



<div class="BAModelName" id="BAModelName">No BA Model Chosen</div>
  <div id="wrapBA"></div>

<div class="MO_ModelName" id="MO_ModelName">No MO Model Chosen</div>
  <div id="wrapMO"></div>

[/code]

abbreviate relevant not_working_overlay_info.php -
[code]
for ($m=1;$m<=12;$m++) {
echo '<div class="availableBADC_'.$m.' "><a href="test.php">'.$m.'</
a></div>';
}
[/code]