Lighttpd

Hello,

I've set up lighttpd 1.4.31 on a debian wheezy server, where I have 3 websites.
For each, I have conf files in /etc/lighttpd/conf-available :
20-site1.conf
20-site2.conf
20-site3.conf

For each, I have set 1 access and 1 error log files :
server.errorlog = "/var/log/lighttpd/site1_error.log"
accesslog.filename = "/var/log/lighttpd/site1_access.log"

...

server.errorlog = "/var/log/lighttpd/site2_error.log"
accesslog.filename = "/var/log/lighttpd/site2_access.log"

...

server.errorlog = "/var/log/lighttpd/site3_error.log"
accesslog.filename = "/var/log/lighttpd/site3_access.log"

I indeed have 3 seperated access.log file. But I don't understand why all errors from the 3 websites are logged in 1 same file, which is site3_error.log ?

Thank you