Apk not upgradable

Hi, I have uploaded the APK that I sent you on Google Play alpha test but I get this advice:

APK not upgradable


No user of this APK can upgrade to a new APK added in this release.


Please check that all your new APKs have been added to this release.

Do you know how to solve this?

Edit: In codename I added a 0 to the end of the number and it works