I am having some issues with the transitions in the editing video section of iMovie. For some reason when I click on some transitions they make the add button grey so I cannot click the add button thus not being able to choose that transition but a select few let me click add and work just fine. All of them still show me a preview in the video window but it will not let me select the transition. I have messed around with it to try it on different length clips and everything but nothing will let me add some transitions. Any one have any ideas on this?