I could solve the problem by using Zxing 2.1 instead of 2.2. like descriped here:
http://khurramitdeveloper.blogspot.ch/p/android-barcode-scan-using-zxing-library.html
And here you can get the Zxing 2.1
https://code.google.com/p/zxing/downloads/detail?name=ZXing-2.1.zip