Problems submitting form after using .getJSON to submit to another site

I have a form that's being validated using jQuery Validate and then submitted to a third-party subscription site.

I'm trying to get the submission posted elsewhere, too.

Here's my form:

<form class="" action="http://www.fakelink.com/forms/userSubmit.jsp" method="post" id="providerDemoForm" accept-charset="UTF-8">    
<fieldset>
  <ul class="undecorated group">
    <li>
      <label for="fld_1_fn">First Name*</label>
      <input type="text" name="First Name" id="fld_1_fn" class="required" onFocus="clearMsg();" />
    </li>
</fieldet>
</form>

Here's my validation script:

<script type="text/javascript">

function postCMFields() {
  $.getJSON(
     "http://sample.createsend.com/x/x/x/fmill/?callback=?",
     $('#providerDemoForm').serialize()
     );
}

$(document).ready(function() {
  $("#providerDemoForm")[0].reset();

  $("#providerDemoForm").validate({
   errorClass: "fieldWithErrors",
   validClass: "valid",
   highlight: function(element, errorClass, validClass) {
     $(element).parent("li").addClass(errorClass);
   },
   unhighlight: function(element, errorClass, validClass) {
     $(element).parent("li").removeClass(errorClass);
   },
   errorContainer: "#formErrorMsg",
   errorLabelContainer: "#messageBox",
   wrapper: "li", debug:false,              

   submitHandler: function(form) {
     $('#formErrorMsg').hide();

     postCMFields();         

     form.submit();

   },
   invalidHandler: function(form, validator) {
     $('#formErrorMsg').show();
   }
  });
});
</script>

Everything submits if I don't have that getJSON part (form submits the action url). If I add in the function to post the contents with JSON to my campaignmonitor url, though, it doesn't work. Furthermore, if I comment out "form.submit()", the data DOES get posted to campaignmonitor.开发者_StackOverflow中文版

Is there something I'm missing? Thanks!

---

I'm not certain why my code wasn't working, but I think it was because my MIME type wasn't set correctly. I was able to get things working by updating my postCMFields function to use .ajax:

var cmdata = $('#providerDemoForm').serialize();

$.ajax({
   type: "GET",
   data: cmdata,
   url: "http://fake.createsend.com/x/x/x/fmill/?callback=?",
   async: false,
   beforeSend: function(x) {
      if(x && x.overrideMimeType) {
         x.overrideMimeType("application/j-son;charset=UTF-8");
      }
   },
   dataType: "json",
   success: function(data){             
      form.submit();
   }
}); 

---

The URL seems fictitious. http://sample.createsend.com/x/x/x/fmill/?callback=? looks like a get URL that you bind variables to.