Hi,
Are you using this line as part of the augmentation once the object is tracked? I think you should use our native sdk as it gives you more freedom to render whatever you want. In particular you should check the object tracking samples in our sample application: https://www.wikitude.com/download-wikitude-sdk-for-android/ where we show how to render a rectangle once the object has been tracked.
Regards,
Aitor.
Rafiq Hilali