fmp6 and fmp9 solutions at once with lasso

setting up the connection between fmp and lasso has always been something i dreaded far more the dentist, so when i installed fmp9 server in order to construct new lasso solutions, i held my breath. since doing this, i've lost my ability for my old fmp6 solutions to operate in lasso, and i've yet to get my fmp9 ones to work. seems like every file i open i get messages about 'can't share due to other user'. in order to get lasso to see the new fmp files thru fmp server, i had to turn off those settings in fmp6 that allowed it to work. is that how its supposed to work--having to change sharing options everytime i want to work on an old or new solution? why do i always get 'file can't be shared' messages everytime i open an fmp9 file? Can't i setup numerous db lasso solutions?