którą wersje bazy masz, że masz pole issuedto?
mysql> describe assignments;
+--------------+--------------+------+-----+---------+----------------+
| Field        | Type         | Null | Key | Default | Extra          |
+--------------+--------------+------+-----+---------+----------------+
| id           | int(11)      | NO   | PRI | NULL    | auto_increment |
| tariffid     | int(11)      | NO   | MUL | 0       |                |
| customerid   | int(11)      | NO   | MUL | NULL    |                |
| period       | smallint(6)  | NO   |     | 0       |                |
| at           | int(11)      | NO   |     | 0       |                |
| datefrom     | int(11)      | NO   |     | 0       |                |
| dateto       | int(11)      | NO   |     | 0       |                |
| invoice      | tinyint(1)   | NO   |     | 0       |                |
| suspended    | tinyint(1)   | NO   |     | 0       |                |
| pdiscount    | decimal(4,2) | NO   |     | 0.00    |                |
| liabilityid  | int(11)      | NO   |     | 0       |                |
| settlement   | tinyint(1)   | NO   |     | 0       |                |
| paytype      | smallint(6)  | YES  |     | NULL    |                |
| numberplanid | int(11)      | YES  | MUL | NULL    |                |
| vdiscount    | decimal(9,2) | NO   |     | 0.00    |                |
+--------------+--------------+------+-----+---------+----------------+
15 rows in set (0.01 sec)

mysql>