App on Google Play Store Crashes without Version 6

[CElwell]

I just put my app on the Google Play store and I have found it works fine for everyone with version 6, but my friends who have tried the app with a lower version get a "native crash." In standalone settings I have 2.3.3 Gingerbread as minimum, but they have version 4 or 5 and it still crashes. Could there be another cause for this? Thank you!