Nothing shows in Preview

I am trying to preview my 1 slide.  When I select Preview, it takes me out to the preview area, chugs along downloading the slide, and when the blue circle stops spinning there is a blank screen.  I am on a trial version and was following along with the tutorial on Creating your first slide so I have built it from scratch but used my own pictures and text.  

Also, in this tutorial, he inserts a shape and then checks the size and position.  His size is 540 X 720.  Mine is the opposite.  What is wrong?  I tried plugging in his sizes as shown and it makes the shape and the background slide not fit each other.

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