Android :: Camera Photo Completely Black

I am creating a little application where I use the Android Camera class. Everything seems to work but the result is a black picture. I think I forget to set a parameter. Do you have any ideas on which parameter I must set up ?

The code:
public boolean takeIt() { ImageCaptureCallback iccb = null;
try { String filename = "photo.jpeg";
ContentValues values = new ContentValues();
values.put(Media.TITLE, filename);
values.put(Media.DESCRIPTION, "Image capture by camera");
iccb = new ImageCaptureCallback(new FileOutputStream(new File (dataMgr.getRoot(), filename)));
} catch(Exception ex ){ ex.printStackTrace();
} camera.takePicture(mShutterCallback, mPictureCallbackRaw, iccb);
return true;
}