HI!
I installed OTRS4 and playing with the settings. I rename the group "admin". The next entry is not possible to get to the administration section. There is simply no links in the interface. If the URL directly dial an error "Message: No Permission to use this frontend module!"
Search issued a decision to restore directly in the database

UPDATE group_user
SET permission_value = 1
WHERE user_id = 1 AND group_id = 2
AND permission_key = 'rw';

But I like in these tables have all the rights

mysql> SELECT * FROM group_user;
+---------+----------+----------------+------------------+---------------------+-----------+---------------------+-----------+
| User_id | group_id | permission_key | permission_value | create_time | create_by | change_time | change_by |
+---------+----------+----------------+------------------+---------------------+-----------+---------------------+-----------+
| 1 | 1 | rw | 1 | 2015-02-19 08:06:39 | 1 | 2015-02-19 08:06:39 | 1 |
| 1 | 2 | rw | 1 | 2015-02-19 08:06:39 | 1 | 2015-02-19 08:06:39 | 1 |
| 1 | 3 | rw | 1 | 2015-02-19 08:06:39 | 1 | 2015-02-19 08:06:39 | 1 |
| 2 | 1 | rw | 1 | 2015-02-19 10:30:53 | 1 | 2015-02-19 10:30:53 | 1 |
| 2 | 2 | rw | 1 | 2015-02-19 10:30:53 | 1 | 2015-02-19 10:30:53 | 1 |
| 2 | 3 | rw | 1 | 2015-02-19 10:30:53 | 1 | 2015-02-19 10:30:53 | 1 |
+---------+----------+----------------+------------------+---------------------+-----------+---------------------+-----------+

Here are 2 of my User
mysql> SELECT id, login FROM users;
+ ---- + ------- +
| Id | login |
+ ---- + ------- +
| 1 | admin |
| 2 | ssv |
+ ---- + ------- +


Where else to look?