Setting up Dirsync for Office 365 - FIM 2010 R2: failed connection :389 Server Down 0x51

Hi,

I have recently installed DirSync on a Windows Server 2008 R2 which is joined to my domain (Domain Level: Windows Server 2008 R2).

After going through DirSync Setup Wizard successfully, the Management Agent "Active Directory Connector" in FIM fails:

Connection Log:

Status                | Time  | Server                            | Error | Error Code
failed-connection | ...      | :389                              | Server Down | 0x51
success               | ...      | dc-2k8.example.net:389 | / | /

Windows firewall and antivirus are turned off.

Any hint would me appreciated a lot. Thanks in advance.