Thanks for your comment.
I've done it that way but after that when I install the BE agent to another Domino server the "Lotus Domino Databases" selection is not available on that server. Don't know why and it seems to be hard to figure it out. The Domino server that I am trying to install the agent is version 8. (published Aug/07) could it be that the BE somehow does not recognize this fresh version of Domino as a Domino server? (Manual says that version 7 and later are supported.)
Anyway, after this unsuccesful attept to install the BE agent to new domino server if I re-install the agent to the old (R6) Domino server the "Lotus Domino Databases" selection will be available there.
Any ideas how to get the agent working? Domino agent licences cost about 800€ a piece so it would be nice to be able to move it from machine to another...