Database Mirroring Error

When I configured database mirroring between two servers in separate DMZ regions, I get the following error on the principle server when I execute the ALTER DATABASE xxxxxxxx SET PARTNER = '****':

The server network address %%% can not be reached or does not exist. Check the network address name and reissue the command. (Microsoft SQL Server, Error: 1418)

Ports have been opened on both machines and I can TELNET both without any problems. I have included the steps that I used.

DATABASE MIRRORING TEST CONFIGURATION
SQL Server 2005 STD
Principal: AA-AAA-AA01
Mirror: BB-BBB-BB07

A. Create certificates for outbound connection on principal server. Refer to
http://msdn2.microsoft.com/en-us/library/ms186384.aspx.
1. In the master database, create a database Master Key.
M:DBADMMIRRORINGCREATE_MAST_KEY_ENCRY
USE master;
CREATE MASTER KEY ENCRYPTION BY PASSWORD = '<1_Strong_Password!>';
GO

2. In the master database, create an encrypted certificate on the server instance.
M:DBADMMIRRORINGCREATE_AA01_MIRRORING_CERT
USE master;
CREATE CERTIFICATE AA_AAA_AA01_MIRRORING_CERT
WITH SUBJECT = 'AA-AAA-AA01 certificate for database mirroring';
GO
SELECT * FROM SYS.CERTIFICATES
GO

3. Create an endpoint for the server instance using its certificate.
M:DBADMMIRRORINGCREATE_AA01_ENDPOINT
CREATE ENDPOINT Endpoint_Mirroring
STATE = STARTED
AS TCP (
LISTENER_PORT=5999
, LISTENER_IP = ALL
)
FOR DATABASE_MIRRORING (
AUTHENTICATION = CERTIFICATE AA_AAA_AA01_MIRRORING_CERT
, ENCRYPTION = REQUIRED ALGORITHM AES
, ROLE = ALL
);
GO

4. Back up the certificate to a file and securely copy it to the other system or systems.
M:DBADMMIRRORINGCREATE_AA01_CERT_BKUP
BACKUP CERTIFICATE AA_AAA_AA01_MIRRORING_CERT
TO FILE = 'M:DBADMMIRRORINGAA_AAA_AA01_MIRRORING_CERT_BKUP.cer';
GO

B. Create certificates for outbound connection on mirror server. Refer to
http://msdn2.microsoft.com/en-us/library/ms186384.aspx.
1. In the master database, create a database Master Key.
M:DBADMMIRRORINGCREATE_MAST_KEY_ENCRY
USE master;
CREATE MASTER KEY ENCRYPTION BY PASSWORD = '<1_Strong_Password!>';
GO

2. In the master database, create an encrypted certificate on the server instance.
M:DBADMMIRRORINGCREATE_BB07_MIRRORING_CERT
USE master;
CREATE CERTIFICATE BB_BBB_BB07_MIRRORING_CERT
WITH SUBJECT = 'BB-BBB-BB07 certificate for database mirroring';
GO
SELECT * FROM SYS.CERTIFICATES
GO

3. Create an endpoint for the server instance using its certificate.
M:DBADMMIRRORINGCREATE_BB07_ENDPOINT
CREATE ENDPOINT Endpoint_Mirroring
STATE = STARTED
AS TCP (
LISTENER_PORT=5999
, LISTENER_IP = PARNTER
)
FOR DATABASE_MIRRORING (
AUTHENTICATION = CERTIFICATE BB_BBB_BB07_MIRRORING_CERT
, ENCRYPTION = REQUIRED ALGORITHM AES
, ROLE = ALL
);
GO

4. Back up the certificate to a file and securely copy it to the other system or systems.
M:DBADMMIRRORINGCREATE_BB07_CERT_BKUP
BACKUP CERTIFICATE BB_BBB_BB07_MIRRORING_CERT
TO FILE = 'M:DBADMMIRRORINGBB_BBB_BB07_MIRRORING_CERT_BKUP.cer';
GO

C. Configure server instances inbound mirroring connections on principal server. Refer to
http://msdn2.microsoft.com/en-us/library/ms187671.aspx.

1. Create a login for other system.
M:DBADMMIRRORINGCREATE_BB07_LOGIN
USE master;
CREATE LOGIN BB07_MIRROR_ADMIN
WITH PASSWORD = '1Sample_Strong_Password!@#';
GO

2. Create a user for that login.
M:DBADMMIRRORINGCREATE_BB07_USER
USE master;
CREATE USER BB07_MIRROR_ADMIN FOR LOGIN BB07_MIRROR_ADMIN;
GO

3. Obtain the certificate for the mirroring endpoint of the other server instance.

4. Associate the certificate with the user created in step 2.
M:DBADMMIRRORINGCREATE_BB07_USER_CERT_LINK
USE master;
CREATE CERTIFICATE BB_BBB_BB07_MIRRORING_CERT
AUTHORIZATION BB07_MIRROR_ADMIN
FROM FILE = 'M:DBADMMIRRORINGBB_BBB_BB07_MIRRORING_CERT_BKUP.cer'
GO

5. Grant CONNECT permission on the login for that mirroring endpoint.
M:DBADMMIRRORINGGRANT_BB07_LOG_ACCESS
USE master;
GRANT CONNECT ON ENDPOINT::Endpoint_Mirroring TO BB07_MIRROR_ADMIN;
GO

D. Configure server instances inbound mirroring connections on master server. Refer to
http://msdn2.microsoft.com/en-us/library/ms187671.aspx.

1. Create a login for other system.
M:DBADMMIRRORINGCREATE_AA01_LOGIN
USE master;
CREATE LOGIN AA01_MIRROR_ADMIN
WITH PASSWORD = '1Sample_Strong_Password!@#';
GO

2. Create a user for that login.
M:DBADMMIRRORINGCREATE_AA01_USER
USE master;
CREATE USER AA01_MIRROR_ADMIN FOR LOGIN AA01_MIRROR_ADMIN;
GO

3. Obtain the certificate for the mirroring endpoint of the other server instance.

4. Associate the certificate with the user created in step 2.

M:DBADMMIRRORINGCREATE_AA01_USER_CERT_LINK
USE master;
CREATE CERTIFICATE AA_AAA_AA01_MIRRORING_CERT
AUTHORIZATION AA01_MIRROR_ADMIN
FROM FILE = 'M:DBADMMIRRORINGAA_AAA_AA01_MIRRORING_CERT_BKUP.cer'
GO

5. Grant CONNECT permission on the login for that mirroring endpoint.
M:DBADMMIRRORINGGRANT_AA01_LOG_ACCESS
USE master;
GRANT CONNECT ON ENDPOINT::Endpoint_Mirroring TO AA01_MIRROR_ADMIN;
GO



E. Back up the Principal Database and copy backup files to mirror server.

F. Restore the Principal Database on the standby database server (use NORECOVERY).

G. Configure the mirroring partners. Refer to http://msdn2.microsoft.com/en-us/library/ms191140.aspx.

1. On the mirror server instance on BB-BBB-BB07, set the server instance on AA-AAA-AA01 as the partner (making it the initial principal server instance).

M:DBADMMIRRORINGACTIVATE_MIRROR_FOR_AA01
--At BB-BBB-BB07, set server instance on AA-AAA-AA01 as partner (principal server):
ALTER DATABASE BESmgmt
SET PARTNER = 'TCP://AA-AAA-AA01.mycompany.com:5999';
GO

2. On the principal server instance on AA-AAA-AA01, set the server instance on BB-BBB-BB07 as the partner (making it the initial mirror server instance).

M:DBADMMIRRORINGACTIVATE_MIRROR_FOR_BB07
--At AA-AAA-AA01, set server instance on BB-BBB-BB07 as partner (mirror server).
ALTER DATABASE BESmgmt
SET PARTNER = 'TCP://BB-BBB-BB07.mycompany.com:5999';
GO

3. Execute the following SELECT on both servers to review mirroring information.
SELECT * FROM SYS.DATABASE_MIRRORING