CKEDITOR没有与承诺回电

Question

     employer_data = functionToGetEmployer();
     $.when(fillData()).then(
      function(status){
        console.log("reaching here");
        if(employer_data.detailsMessage !== null){
         console.log("reaching here too");
CKEDITOR.instances.employer_detail_message.setData(employer_data.detailsMessage);
        }
      }
    )

    fillData: function(){
      var dfd = jQuery.Deferred();

      $.ajax({
        // some ajax call to get some data.

        success: function(){
          // do something
          dfd.resolve("resolved");
        },
        error: function(){
          dfd.reject("rejected");
        }

      })
       return dfd.promise();
    }

在上面，ckeditor setData方法无效。

如果我将setData方法保留在promise设置之上，那么它会按预期工作。