Ok, I have made an update.
Some authors did not have tip-info, thats why there were no result for them.
This is fixed.
I also look again at the non-valid isbn and fixed it also.
. When parsing the isbn I started with the second number.
It took me a lot of time, to make it work with that error.
With the correct startposition there isn't a problem at all.
for testing and copmment