Unable to Start Activity, Activity can't be Null, but Activity is in Manifest?

Question

In the Google Play crash reporter, I'm getting a few unexpected crash reports, and was wondering if some light could be shed as to the cause.

The crash report is this:

Caused by: java.lang.RuntimeException: Unable to start activity 
ComponentInfo{com.hvs.tt/com.prime31.FacebookProxyActivity}: 
java.lang.IllegalArgumentException: activity cannot be null
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2205)

In my manifest, I do have that activity declared inside my "application" section:

<activity android:name="com.prime31.FacebookProxyActivity"></activity>

And my application bundle ID is com.hvs.tt as well. Compounding confusion is that this does seem to work on all of my test devices, but it shows up organically on the app store from time to time. Is this something I can fix, or is it an issue with a specific users device???