I seems to be a problem with the german version of ZC. I have installed the english version on another pc, and there I could install the testimonial manager without any problems.
In the english version there is no language_id in the database, but in the german version you can find it. So it is no wonder that i always get an error report.

With some help of my husband the sql patch now runs without problems. But i have to use the english language in the german version of zc to see the menue of testimonial manager.

I hope you understand what I mean.