actually I've copied an existing config file and renamed it for a new statistic.
I searched for some hours where's the problem was that the new config file didn't work.
I found out that I started the awstats.pl command with the parameter -config=virtualhostname while staying in a folder which does include a subfolder with the same name - and this was the error.
The debug parameter wrote that it reads the config but does not find some parameters in it. So I was confused.
Long text, short end:
After entering -config=/path/to/virtualhostname.conf it surprisingly worked!
Awstats searches for different places for the defined config file.
Please add the function that it checks if the config file is really a file - not a directory.