Well, it could simply be a problem with your zipping of the file. If you are using WinRar, first right click on the ENTITIES folder, not whatever folder you have that in (ex. Lion Varient). After you right click that, hit "Add to archive" then select ZIP not RAR. Once that's done, make sure you give your file a name, and end it with .z2f NOT .zip Then, place it in your C:\Program Files\Microsoft Games\Zoo Tycoon 2 folder, as that seems to work better than placing it in the downloads folder.