Automessage plug in activation cause the page cannot display

Dear Support,

Whenever I tried to activate the plug-in. It is activated.

however, when I refresh the front end page I got the error below:
Fatal error: Cannot redeclare mysql2date() (previously declared

I am using:

1- WP 3.2.1 Multi site (sub domain)
2- Using Multi DB (16database)

Thanks,
Regards,
Socheat