Problems...again

The effects I want and need to use on my video are not working which is causing me to get a little behind. We are 40 minutes into the lesson and I haven't done any of my video so far this lesson as I am spending my time faffing about trying to get the crop effect to work. This is really frustrating as it has worked for other students but for some reason now isn't working for me. I am going to have to either get on with another part of my video which I do not want to do as I'd like to do it chronologically or get on with my digi pack. Although it will not solve the problem so my best bet it so scrao the shots and effects I want to use and find something else.