From your screen-shots I assume you have following:
You are using one directory server for vCO user authentication and an AD for managing by AD plug-in.
If this is the case, the problem is most probably related to that your vCO admin user is not a user of AD, configured in plug-in, and because of that AD refuses to connect.
To resolve the issue, please, check 'Use a shared session' in AD plug-in configuration page and add user credentials of a user with enough privileges to be able to fulfill your administration tasks.
If you do not intend to use shared session, then vCO should use this AD to authenticate users.
If my assumption is not correct, then, please, can you explain your use case and can you give more details:
What is the version of AD?
What is the version of vCO?
Any logs from vCO will help also. They are: <vco install folder>\app-server\server\vmo\log\server.log