Yes, I'm sure about this, I can vi it.
I'll try with relative path in a few minutes
edit : Did try some things and achieved to finally understand..
I removed the @ in front of the fopen function, showing me the error returned.
When using the correct path : Warning: fopen(/usr/local/apache/domlogs/domain.com): failed to open stream: Permission denied in /admincp/apache_logs.php on line 39

Got it working by chmodding the logfile (is 555 right ?)