Custom subscriptions not adding items to notifications_event table

I have 2 Drupal 6.12 sites running on same code base (multisite).
I have the same modules enabled in both sites.
In one site I managed to get custom subscriptions working after fooling around with it for 2 days. It just started working suddenly and it was not from any settings I changed.
The second site, when set up exactly the same way, will still not send any mail notifications for custom subscriptions.
(Both sites will always send standard [non-custom] subscription notifications.)

I compared the db tables for the site that works (Example_Site1Drupal) and the site that does not work (Exampl2Drupal). The comparision is attached as a text file. Here is the main difference:

mysql> use Example_Site1Drupal; (working)
mysql> select * from notifications_event;
+-----+--------+------+--------+-----+----------+------+---------------------------+------------+---------+
| eid | module | type | action | oid | language | uid | params | created | counter |
+-----+--------+------+--------+-----+----------+------+---------------------------+------------+---------+
| 19 | node | node | update | 73 | NULL | 1 | a:1:{s:3:"nid";s:2:"73";} | 1243276058 | 0 |
| 18 | node | node | update | 77 | NULL | 1 | a:1:{s:3:"nid";s:2:"77";} | 1243275518 | 0 |
+-----+--------+------+--------+-----+----------+------+---------------------------+------------+---------+
2 rows in set (0.00 sec)

mysql> use Exampl2Drupal; (not working)
mysql> select * from notifications_event;
Empty set (0.00 sec)

Here's my Drupal info: Drupal 6.12

Modules
FCKeditor - WYSIWYG HTML editor 6.x-2.0-alpha5
Global Redirect 6.x-1.2
Image 6.x-1.0-alpha4
Messaging 6.x-2.0
Mollom 6.x-1.7
Notifications 6.x-2.x-dev (2009-May-18)
Notifications Add-ons 6.x-2.x-dev (2009-Apr-28)
Recommended version: 6.x-2.0-beta2 (2009-Apr-29)
Pathauto 6.x-1.x-dev (2009-May-02)
SMTP Authentication Support 6.x-1.0-beta3
Token 6.x-1.x-dev (2009-Apr-20)
Watcher 6.x-1.2
Themes
Marinelli 6.x-2.95