Jquery Inline form validation how to disable submit button

jQuery("#formname").validationEngine('attach', {

            onValidationComplete: function (form, status) {

                if (status == true) {

                    $('#Btname').attr('disabled', true);

                    return true;

                }

            }

        });

jQuery("#formname").validationEngine('attach', {

                onValidationComplete: function (form, status) {

                    if (status == true) {

                        $('#Btname').attr('disabled', true);

                        return true;

                    }

                }

            });