Multi-master replication - The slave synchronized to mid (no replies)

Hi to all,
I have a problem with the synchronization between two master and one slave.

I built this scheme:

> M1 has the Database db1
> M2 has the Following characteristics
Slave of M1
Db1 database tables to use BLACKHOLE Storage Engine
Db2 database has real date
> S1 has the Following characteristics
Slave of M2
Database db1 has real date
Db2 database has real date

By insert a data on db1 in M1, is replicated correctly in M2 and Slave.

But if I insert a data on db2 in M2, it is not updated on the Slave.

I post configuration, hoping to understand why the synchronization between M2 and S1 occurs partially.

Can you help me?
Thanks
Andrea

M1

mysql> SHOW MASTER STATUS \G;
*************************** 1. row ***************************
File: mysql-bin.000163
Position: 120758
Binlog_Do_DB: fraudpagetracker
Binlog_Ignore_DB:
1 row in set (0.00 sec)

ERROR:
No query specified

mysql> SHOW SLAVE HOSTS;
+-----------+------+------+-----------+
| Server_id | Host | Port | Master_id |
+-----------+------+------+-----------+
| 12 | | 3306 | 11 |
+-----------+------+------+-----------+
1 row in set (0.00 sec)


M2

mysql> SHOW MASTER STATUS \G;
*************************** 1. row ***************************
File: master2-bin.000012
Position: 264642
Binlog_Do_DB: xcasatracker,xcasa_ew,xcasa_gener
Binlog_Ignore_DB:
1 row in set (0.00 sec)

ERROR:
No query specified

mysql> show slave hosts;
+-----------+------+------+-----------+
| Server_id | Host | Port | Master_id |
+-----------+------+------+-----------+
| 111 | | 3306 | 12 |
+-----------+------+------+-----------+
1 row in set (0.00 sec)

Slave

mysql> SHOW SLAVE STATUS \G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: XXX.YYY.ZZZ.QQQQ
Master_User: replicator
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: master2-bin.000012
Read_Master_Log_Pos: 265508
Relay_Log_File: mysql-relay-bin.000002
Relay_Log_Pos: 4585
Relay_Master_Log_File: master2-bin.000012
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 265508
Relay_Log_Space: 4741
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 12
1 row in set (0.00 sec)