what is your domain name, lets say if its example.com should you not be using dc=example,dc=com
else try something like this from the CMD of the system where AD is installed
dsquery user dc=example,dc=com -name user1
in this example my domain is example.com and user name is user1, edit the command as per requirement
Usually below is how i set up my env
search base : dc=example,dc=com
Bind DN = example\administrator