Buddypress Internal Forum: Any tables to be added for Multi-db?

I have setup the internal buddypress forum but still doesn't seem to work.

I use the multi db plugin, so are there any tables that need adding? if so, any idea what it would be?

I'm sure that is what this message is referring to:

NOTE: The forums directory will only work if your bbPress tables are in the same database as your WordPress tables.