ajaxSubmit enables disabled fields

I have some disabled=true fields, but then I submit a form using ajaxSubmit(), all disabled fields become enabled. What I have to do to keep fields disabled?

From stackoverflow

• You can do that within the success callback option, e.g.:

  var options = {
      url:         '/some/url',
      type:        'post',
      target:       '#resultsDiv',
      success:       function() { $("#foo").attr("disabled","disabled");  }
  };