Android : NullPointerException: Can't inject null value into class - field is not @Nullable

I'm using RoboGuice, however I keep getting a NullPointerException Can't inject null value into class com.jjm.android.game.first.QuestionFirst.mPuzzleText when field is not @Nullable

I've no idea how to get around this issue.

Anyone have any recommendations ? Thanks

10-10 02:20:39.201: E/AndroidRuntime(18809): FATAL EXCEPTION: main
10-10 02:20:39.201: E/AndroidRuntime(18809): Process: com.app.android.app, PID: 18809
10-10 02:20:39.201: E/AndroidRuntime(18809): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.app.android.app/com.jjm.android.game.activity.MainActivity}: java.lang.NullPointerException: Can't inject null value into class com.jjm.android.game.first.QuestionFirst.mPuzzleText when field is not @Nullable