active directory with call CN or OU f5 login authentication

Hi,

So could i ask what you are trying to achieve?
Is this part of a APM policy? or are you trying to setup log into the f5 using ad/ldap external auth?

My first guess is the Attribute String you have told the f5 to query is lower than the user you are looking for. But i could be wrong! and a little context would be helpful.