Restore dump - missing privileges on new server

[Marc Wenger]

Hello, I'm using a procedure to restore the production DBMS to a Test DBMS once a week on a different machine.
My problem is that the data and DBs are restored correctly but I miss the priviledges on the db.

to Backup my database I use this procedure:

mysqldump -u root -p --all-databases --flush-logs > mysql-AllDB-dump.sql

here is the point. when I look into the mysql-AllDB-dump.sql I see all users configured into the "INSERT INTO user VALUES" command but when I restore it only the root user has permissions.

here the restore command:
mysql -u root -p < mysql-AllDB-dump.sql

when I run this command on the source server (Prod)
SHOW GRANTS FOR 'wmnet'@'localhost';

I get the right result:

+----------------------------------------------------------+
| Grants for wmnet@localhost |
+----------------------------------------------------------+
| GRANT USAGE ON *.* TO 'wmnet'@'localhost' |
| GRANT ALL PRIVILEGES ON `wmnet`.* TO 'wmnet'@'localhost' |
+----------------------------------------------------------+
2 rows in set (0.00 sec)

but when i run the same command i get the error:
ERROR 1141 (42000): There is no such grant defined for user 'wmnet' on host 'localhost'

What am I missing to restore the right privileges?

Thanks for help