Look in your /etc/awstats/awstats.
www.yourdomain.com.conf file, and search a line like this...
LogFile="/var/www/webX/log/web.log"
Your awstats make stats from /var/www/webX/log/web.log file, if this file it's empty, I think you have a problem with your apache log system.
I sorry, but I'm not an expert and I can't help much more... ;(