[horde] Mnemo Driver Fatal Error

[Simon Brereton]

Hi

I added Mnemo 4.0.0beta1 to my Horde5 install.  DB schema is ready,
Application is ready, but when I click on the tab I get this:

A fatal error has occurred
Unable to load the definition of Mnemo_Driver_.

1. require() /usr/share/horde-beta/mnemo/index.php:11
2. Mnemo::listMemos() /usr/share/horde-beta/mnemo/list.php:26
3. Mnemo_Factory_Driver->create() /usr/share/horde-beta/mnemo/lib/Mnemo.php:87

Details
The full error message is logged in Horde's log file, and is shown
below only to administrators. Non-administrative users will not see
error details.

Any help would be appreciated.