[exim] Change Exim's log_file_path (it's not working)

Hello,
I'm using the mail packet of eisfair and started reading up a bit about
exim (which is part of the packet) to get its log files to a different
location. So I added log_file_path = /somepath/%s.log in the general
section (before any "begins") of the exim config file and restarted the
mail packet. Then I looked at the config file (yes it's owner and r/w
rights are correct) to make sure my entry was still there. Yet the
logfiles did not appear at my path (yes the folder exists) and all
logging was still done at /var/spool/exim/log. What's up with that?

Philipp