FTP Statistics not working

[Martini]

A few days ago I switched from ProFTPd to PureFTPd, since then this error is no longer existent :
[DEBUG] push_el() sub_name: gen_log_file(), msg: Starting for logfile /var/log/proftpd/ftp_traff.log
[DEBUG] push_el() sub_name: gen_log_file(), msg: Taking the domain log positions from '/var/log/ispcp/logdb'...
[DEBUG] push_el() sub_name: gen_log_file, msg: Logfile contains no data, so skip it for now.

but my logs in ispcp are still dead, showing 0 B transferred.

Any help would be appreciated,
Martini