Why Do Guests Stop Coming To Parks

I'm playing Arid Heights.  It's April Year 8 and no one comes anymore.  My Park Rating has been in the 800s and 900s

thanks,

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The Roller Coaster Collection:
With A New Poll and More Stuff Coming Soon:
http://www.angelfire.com/extreme2/rollercoaster2/index.html

It's a bug in the LL game. Download the patch at the official site http://www.rollercoastertycoon.com/test/downloads/patches.html and that will fix the problem (happens in the first 10 scenarios after a specific amount of research has been completed).