schema_version

4.7 upgrade script cannot determine correctly my system module's version. I've checked the db, and found this:

mysql> select schema_version from system where filename="modules/system.module";
+----------------+
| schema_version |
+----------------+
| -1 |
+----------------+
1 row in set (0.00 sec)

My old Drupal version is 4.6.6. What is the correct shema_version for 4.6.6? It should be "128"?