How do I snap the rear casing back on?

I was taking off case and caught the top of my Kindle Voyage with my nail and the top of the rear casing separated. When I looked into it, this is how the back is supposed to come off...iFixit even shows that this is how you begin taking it apart. All advice I can find says to just snap it back together but, try as I might, I can't pinch the clips hard enough to get them to click. Please recommend a strategy, I don't want to cause damage in trying to fix such a simple problem. Thanks!