Application TabHost erreur

Bonjour, j'essaye actuellement de créer une application android sous android studio 2.1 en suivant ce tutoriel : http://www.androidpeople.com/android...utorial-part-1
Mais quand je compile mon projet, j'ai l'erreur suivant :
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05-03 11:56:39.338 26309-26309/com.example.guillaume.sensortag_app E/AndroidRuntime: FATAL EXCEPTION: main
                                                                                     Process: com.example.guillaume.sensortag_app, PID: 26309
                                                                                     java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.guillaume.sensortag_app/com.example.guillaume.sensortag_app.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TabWidget.addView(android.view.View)' on a null object reference
                                                                                         at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2695)
                                                                                         at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2769)
                                                                                         at android.app.ActivityThread.access$900(ActivityThread.java:177)
                                                                                         at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1430)
                                                                                         at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                                         at android.os.Looper.loop(Looper.java:135)
                                                                                         at android.app.ActivityThread.main(ActivityThread.java:5910)
                                                                                         at java.lang.reflect.Method.invoke(Native Method)
                                                                                         at java.lang.reflect.Method.invoke(Method.java:372)
                                                                                         at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1405)
                                                                                         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1200)
                                                                                      Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TabWidget.addView(android.view.View)' on a null object reference
                                                                                         at android.widget.TabHost.addTab(TabHost.java:252)
                                                                                         at com.example.guillaume.sensortag_app.MainActivity.onCreate(MainActivity.java:37)
                                                                                         at android.app.Activity.performCreate(Activity.java:6178)
                                                                                         at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
                                                                                         at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2648)
                                                                                         at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2769)*
                                                                                         at android.app.ActivityThread.access$900(ActivityThread.java:177)*
                                                                                         at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1430)*
                                                                                         at android.os.Handler.dispatchMessage(Handler.java:102)*
                                                                                         at android.os.Looper.loop(Looper.java:135)*
                                                                                         at android.app.ActivityThread.main(ActivityThread.java:5910)*
                                                                                         at java.lang.reflect.Method.invoke(Native Method)*
                                                                                         at java.lang.reflect.Method.invoke(Method.java:372)*
                                                                                         at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1405)*
                                                                                         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1200)*
L'erreur doit être toute bête mais ça fait 6 heures que je suis dessus et que j'essaye différent tutoriel etc... mais toujours le même type de problème.