URGENT, can't initialize avast! engine: Unknown error

anyone can tell me what wrong and how to debug? Thanks a lot!

Jun 29 13:56:01 avastd[950]: info: Starting avast! daemon
Jun 29 13:56:01 avastd[950]: info: listenning on ‘127.0.0.1:5036’
Jun 29 13:56:01 avastd[950]: info: start new process (‘avast4mail’, pid=953)
Jun 29 13:56:03 avastd[950]: error: ‘avast4mail[953]’: can’t initialize avast! engine: Unknown error
Jun 29 13:56:03 avastd[950]: info: ‘avast4mail[953]’: closing process
Jun 29 13:56:03 avastd[950]: info: avast! server: closing avast! server ‘127.0.0.1:5036’
Jun 29 13:56:03 avastd[950]: info: Quitting avast! daemon

upgrade your avast! engine to the latest available version (libavastengine-4.6.3-i586.tar.gz or RPM package)

http://www.avast.com/cze/download-avast-for-linux-server.html