Give the cacti user permission to read the internal MySQL table for time zone names:

[j5@linux ~]$ mysql -u root -p mysql
mysql> grant select on mysql.time_zone_name to cactiuser@'%';
Query OK, 0 rows affected (0.00 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

mysql> quit

To populate MySQL with some Timezone information:

[j5@linux ~]$ mysql -u root -p mysql < /usr/share/mysql/mysql_test_data_timezone.sql 
Enter password:

Now there’s at least some stuff there:

mysql> select * from time_zone_name;
+--------------------+--------------+
| Name | Time_zone_id |
+--------------------+--------------+
| MET | 1 |
| UTC | 2 |
| Universal | 2 |
| Europe/Moscow | 3 |
| leap/Europe/Moscow | 4 |
| Japan | 5 |
+--------------------+--------------+
6 rows in set (0.00 sec)