NoClassDefFoundError com.ericsson.research.owr.OwrBridge

I am trying to develop a Google Glass App using Open WebRTC.
I have imported `openwebrtc.jar` and `openwebrtc_bridge.jar` into my project:


Why do I get this error:

```
E/AndroidRuntime(7826): FATAL EXCEPTION: main
E/AndroidRuntime(7826): Process: *my package name*, PID: 7826
E/AndroidRuntime(7826): java.lang.NoClassDefFoundError: com.ericsson.research.owr.OwrBridge
E/AndroidRuntime(7826): at *my package name*.CallActivity.onCreate(CallActivity.java:26)
E/AndroidRuntime(7826): at android.app.Activity.performCreate(Activity.java:5235)
E/AndroidRuntime(7826): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1089)
E/AndroidRuntime(7826): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2188)
E/AndroidRuntime(7826): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2273)
E/AndroidRuntime(7826): at android.app.ActivityThread.access$800(ActivityThread.java:138)
E/AndroidRuntime(7826): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1236)
E/AndroidRuntime(7826): at android.os.Handler.dispatchMessage(Handler.java:102)
E/AndroidRuntime(7826): at android.os.Looper.loop(Looper.java:149)
E/AndroidRuntime(7826): at android.app.ActivityThread.main(ActivityThread.java:5045)
E/AndroidRuntime(7826): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(7826): at java.lang.reflect.Method.invoke(Method.java:515)
E/AndroidRuntime(7826): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
E/AndroidRuntime(7826): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:602)
E/AndroidRuntime(7826): at dalvik.system.NativeStart.main(Native Method)
11-10 14:02:04.433: I/Process(7826): Sending signal. PID: 7826 SIG: 9
```

Do I have to add more than just the two .jar-files?