The Cisco VPN3000 has a menu interface that CatTools accesses by sending a string of menu item numbers that invokes the display of the config.
The older VPN IOS prior to V4.0 uses 2.6.3 as the menu sequence. The Cisco Other VPN3000 uses this string by default.
The later IOS, V4.1, uses 2.8.3 as the menu sequence. The Cisco 4.1 VPN3000 uses this by default.
The intermediate V4.0 IOS requires 2.7.3.
If neither of the VPN3000 device types backup your device, try using the alternate command field of the backup activity and enter 2.7.3.
Note that if you use an alternate command it overrides the default commands for all selected devices in the activity.