Gmail app opens Google Play Store

I activated the Google Play Store, and everything works great except for the Gmail app.  If I open Gmail from a notification or search for Gmail in the Play Store and press "open," Gmail will open.  However, if I click on Gmail from the App screen, it opens the Google Play Store instead.  I tried uninstalling and reinstalling Gmail, and it has the same behavior.  I also tried what this user recommended, but the app still opens the store and not Gmail.