--- sites/all/modules/contrib/availability_calendars/availability_calendar.viewport.js	(date 1362577796000)
+++ sites/all/modules/contrib/availability_calendars/availability_calendar.viewport.js	(revision )
@@ -141,7 +141,8 @@
 
   function initAnimation() {
     if (!viewportSettings.animate.custom) {
-      var isLtr = $('html').attr('dir') === 'ltr';
+      var isLtr = (typeof $('html').attr('dir') === 'undefined') ? true : ($('html').attr('dir') === 'ltr');
+
       viewportSettings.animate.backward = viewportSettings.rows > 1 ? { top: "+=" + (viewportSettings.scroll * viewportSettings.month.height) }
         : isLtr ? { left:  "+=" + (viewportSettings.scroll * viewportSettings.month.width) }
         : { right: "+=" + (viewportSettings.scroll * viewportSettings.month.width) };
@@ -196,6 +197,7 @@
    */
   this.scrollForward = function() {
     if (viewportSettings.firstMonth + viewportSettings.rows * viewportSettings.cols <= viewportSettings.totalMonths) {
+
       viewport.animate(viewportSettings.animate.forward, viewportSettings.animate.speed);
       viewportSettings.firstMonth += viewportSettings.rows > 1 ? viewportSettings.scroll * viewportSettings.cols : viewportSettings.scroll;
       setEnabledState();