We are 3 persons about to use the database but if it is open on my computer, It gives error on my friends computer.
It is an another problem, another task. Please create for this a new topic. (If that 'database' is a real database, then create a topic in the Base forum.
Just a tip:
We (a little ltd.) are using a Calc template file as Address book for create 'email attachment letters' to our clients. (I can not use the databases, because I do not know the technology of the databases.)
The template file will open on more than one network computer (as "Unnamed1" file) without any problem. Note: It is a workaround only, but not a professional solution.