squirrelmail blank page

i install debian 12 in vmware for my training. i want to setup as server. i already set static ip, setup dns, web server, postfix, dovecot. i also already apt update. when i test my web with my domain, all ok. i use squirrelmail 1.4.22. i download, unzip dan mv to /var/www/mail/squirrelmail. i already add my DocumentRoot /var/www/mail/squirrelmail and ServerName with mail.example.org.my. i type mail.example.org.my in firefox but the login page is blank. just appear mail.example.org.my/src/login.php. may anybody help me.