I have one farm with two web application ("training" and "test") which are installed od 2 servers (for NLB purpose). Web apps use claims based auth (win & fba). Both web applications use same aspnetdb database on third server. When I want to add aspnetmembership user to "test" SP group (e.g. "admins" or "team members") everything pass ok, but when I want to add same user to "training" SP group, i got error "User does not exist or it is not unique".
Above thing is totally weird because I manage to login with that user(on "training" web app), but adding to "training" SP group is not possible.
PLEASE any suggestion!