ERROR 1044 (42000): Access denied for user ''@'localhost' to database 'xyz'

[Dusty Maus]

I installed MySQL 5.5, logged in as root, created a new database

CREATE DATABASE hgkwin;

then created a new user

CREATE USER 'jutta';

and added all privs to her:

grant all privileges on hgkwin.* to 'jutta';

I checked it:

mysql> show grants for 'jutta';
+---------------------------------------------------+
| Grants for jutta@% |
+---------------------------------------------------+
| GRANT USAGE ON *.* TO 'jutta'@'%' |
| GRANT ALL PRIVILEGES ON `hgkwin`.* TO 'jutta'@'%' |
+---------------------------------------------------+
2 rows in set (0.00 sec)

and logged in as jutta:

mysql -u jutta

Unfortunately I can't access the db:

mysql> use hgkwin
ERROR 1044 (42000): Access denied for user ''@'localhost' to database 'hgkwin'

I checked my rights as jutta:

mysql> show grants for current_user;
+--------------------------------------+
| Grants for @localhost |
+--------------------------------------+
| GRANT USAGE ON *.* TO ''@'localhost' |
+--------------------------------------+

but no way to reach my database 'hgkwin'.

What's wrong???