Use ADInsight to verify what might be causing the connection issue.
ADInsight is a sysinternals tool from Microsoft that you can download for free:
http://technet.microsoft.com/en-us/sysinternals/bb897539
It is an LDAP real-time monitoring tool aimed at troubleshooting AD client applications. Running ADInsight at the time you are trying to access AD via CMN configuration will inform why CMN is failing when accessing AD.
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