make sure your active cursor is "blinking" where you need to insert your keyframe. I say this because I believe there are a couple ways to sync your changes. Just so you know VMS is sooooo powerful you can tell it which frame you want to start and which frame you want it to stop. If you manually select the transition you want to alter you should see a place (lower right for me) that indicates the key frame where you can adjust the transitions. I am stirring up cobwebs here but I think if your preferences are set to sync with the cursor if you arent careful you can get a wee bit lost. hehe John I am sure if I am off someone will straighten me out. In any case KEYFRAME is what you need to look at.

good luck