This works without SSL as well. 
 Here's my working config, it be of might help.. 
 bindDN = CN=ldapquery,OU=Services,DC=test,DC=com  
bindDNpassword = aPassword  
charset = utf8  
groupBaseDN = CN=Splunk_Admins,OU=Groups,DC=test,DC=com;CN=Splunk_Power_Users,OU=Groups,DC=test,DC=com;CN=Splunk_Users,OU=Groups,DC=test,DC=com  
groupMappingAttribute = dn  
groupMemberAttribute = member  
groupNameAttribute = cn  
host = testDC.test.com  
nestedGroups = 0  
network_timeout = 20  
port = 389  
realNameAttribute = cn  
sizelimit = 1000  
timelimit = 15  
userBaseDN = OU=Users,OU=MyUsers,DC=test,DC=com  
userNameAttribute = samaccountname 
						
					
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