Because the IFFWDMmkII card is new to the Tascam line, most existing mixers will require a software update to work with the new card.
Required mixer versions are:
DM3200 v1.30 or later, supplied on Included CD ROM (only works in Slot1)
DM4800 v1.10 or later, supplied on Included CD ROM (only works in slot 1 or 3)
This can be verified by going to Alt+Utility and then to the System page on either mixer.
To update the mixer, use the TMCompanion software and the updates from the CD ROM included with the card.