Passing AJAX data - Result is missing formal parameter

Passing AJAX data - Result is missing formal parameter

Hi,

Trying to pass two data entities in AJAX;  See below CODE and ERROR.

Am I trying to do something you can't do here? Help appreciated.

R

  1.         $('button[name="create"]').click( function() {
            successMsgShow();
                $.ajax({
                    type: "POST",
                    url: "AccountAdd.php",
                    data: {"mykey":mykey, $('form#acctForm').serialize()},
                    success: storeData                          
                }); // ajax                                  mykey is a var declared elseware.
         
            })

detailed error:
SyntaxError: missing formal parameter