(1) Explain your problem, don't simply post "This isn't working". What were you doing when you faced the problem? What have you tried to resolve - did you look for a solution using "Search" ? Has it happened just once or several times?
(2) It's also good to get feedback when a solution is found, return to the original post to explain how it was resolved so that more people can also use the results.
P6 database does not automatically synchronised the update when both users open same project. The user who update the data should press F5 to refresh the database and reflect the update then the other user need to do the same by pressing F5 to refresh the current screen and the updated information will be refresh and reflect for both users.