I had the same problem in the past. The reason was in external lightbox plugin which was installed after robo gallery installation.
After suggestion of the robo gallery support we just switch jQuery settings in general gallery settings (in left side menu of the wordpress admin section / settings sub menu below Robo Gallery menu item).
Also do not forget to turn off cache. Couple of times cache was the reason of incorrect load of the modifications. When you configuring gallery you need to turn off cache and enable it back when you finish configuration.
