Почему при первом клике outerHeight() = null?

$(".bottom__m").stick_in_parent();
            $('.bottom__m a[href^="#"]').bind('click.smoothscroll',function (e) {
                e.preventDefault();
                var istuckHeigh = $(".bottom__m.is_stuck").outerHeight();

                var target = this.hash,
                    $target = $(target);

                $('html, body').stop().animate({
                    'scrollTop': $target.offset().top - istuckHeigh + 30
                }, 900, 'swing', function () {
                    //window.location.hash = target;
                    if(history.pushState) {
                        history.pushState(null, null, target);
                    }
                    else {
                        location.hash = target;
                    }
                });
                console.log(istuckHeigh);
                return false;
            });