FTP authentication on Solaris can still be working fine, but the syslog will have entries such as this:
Jun 5 07:05:20 hostname1 ftpd: [ID 776383 auth.error] open_module: stat(/opt/quest/lib/security/pam_vas3.so) failed: No such file or directory
Jun 5 07:05:20 hostname1 ftpd: [ID 487707 auth.error] load_modules: can not open module /opt/quest/lib/security/pam_vas3.so
The Solaris FTP daemon (based on WU-FTP) has a feature called Virtual Servers where a number of Virtual FTP sites can run on a single host with different configurations and root directory structures, similar to a chroot jail.
These errors in syslog can occur when a virtual FTP server was created before Quest Authentication Services (QAS/VAS) was installed, and as a result, does not have the pam_vas3.so PAM module in its directory structure.
Copy the pam_vas3.so, including the complete path, into your virtual FTP host directory structure.