Problem using select-chain, getting Ajax parser error.

Problem using select-chain, getting Ajax parser error.

I'm trying to incorporate Remy's select-chain plug-in into my code, and I'm having troubles. I hope someone can take a minute or two to help me.
My situation seemed simple, only 2 levels, Products and Programs under each Product. I have the back-end working, so it returns the JSON list of Programs when a Product ID is passed. However, the plug-in keeps failing in the .ajax() function, tripping the error(). It reports a "parsererror", so I know I've messed up something.
One wrinkle, I have multiples of the Product/Program pairs on my page, identified as "prod_x"/"prog_x", so I need to dynamically call them. Here is my code:

  1.   var pgmid;
      $('select[id^="prod_"]').change(function(){
       var prodid = $(this).attr('ID');
       pgmid = "prog" + prodid.substring(prodid.indexOf('_'));
    //alert("Program ID = " + pgmid);
      }).selectChain({
    //   target: $('#' + pgmid),
       target: $('#prog_0'),
       url: "edit_ajax.php?id=" + $(this).val(),
       data: { ajax: true } // , id: $(this).val()
      });









I'm not sure how to get the linked Program element correctly. Calling the "change()" first to assign the pgmid should work, but it isn't.  But even when I hard-code the "prog_0", it still doesn't work.

Another note, when I display the error message from the select-chain plug-in, I get this:
"jQuery15076..._13009... was not called".  The first part of the jQuery string matches the jQuery field from my jQuery execution, but there is an underscore, then a bunch of other numbers after it.  That sounds off to me.
 
Any help would be much appreciated.
Thanks.