Hi,

I work with Max Enterprise (5 licences)and we cannot log as MASTER while the 5 users are using MAXIMIZER. Can you help me?

That's how it's supposed to act. If you have a 5 user license with 5 people logged in to Maximizer and you try to log on at a 6th machine as MASTER, you're not going to get in. The user license restricts the number of concurrent connections to the database.

Logging in as MASTER counts against your user count. If you need to get in as MASTER, have one of the other people log out. Or, buy more licenses.