Why the user 'sa' can not login a new database which I great?
And I can not add the user 'sa' to the new database.

are you login in using windows authentication on the network. if so, your are using the domain account to login in to SQL. SA account is created automatically when SQL is setup and is the a local sql system administrator it is and has ownership over all objects

go to enterprise manager
right click on your register server
select edit registered server
select use sql server authentication
type in SA for user login name
type your sa password

make sure all three selection at the bottom are select

once you have done this check that you have access to your registered server.

Create other account that are needed, avoid using the sa account for routine day to day activities.

Jaime E. Maccou

Thanks for your help.