Sorry, my bad. I didn't pay close attention to the error message:
Code:
unresolved external symbol _deflateEnd
You are missing zlib.lib from your linker input dependencies. Maybe you are running your own configuration? Go to the properties for your project, find the Linker/Input tab, and add zlib.lib to the "Additional Dependencies".
I suspect that since this is not part of your dependency list, something funky is happening. Are you compiling the "Debug" or "Release" configurations?