org.renpy.android.PythonSDLActivity cannot be found

[Meg58]

A user tried to play to the game I released on Google Play and met this error. The game cannot launch on his device because of this. Can someone help me solve this? Thanks!

java.lang.NoClassDefFoundError: org.renpy.android.PythonSDLActivity$1
   at org.renpy.android.PythonSDLActivity.setupMainWindowDisplayMode(PythonSDLActivity.java:99)
   at org.renpy.android.PythonSDLActivity.onResume(PythonSDLActivity.java:140)
   at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1150)
   at android.app.Activity.performResume(Activity.java:3832)
   at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2114)
   at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2139)
   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1672)
   at android.app.ActivityThread.access$1500(ActivityThread.java:117)
   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
   at android.os.Handler.dispatchMessage(Handler.java:99)
   at android.os.Looper.loop(Looper.java:130)
   at android.app.ActivityThread.main(ActivityThread.java:3687)
   at java.lang.reflect.Method.invokeNative(Native Method)
   at java.lang.reflect.Method.invoke(Method.java:507)
   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:842)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
   at dalvik.system.NativeStart.main(Native Method)