[Koha] Koha - Active Directory LDAP struggles

[Michael BC]

I've tried searching the archives and can't seem to find the answer. When
we use a correct username/password, the login page generates a Software
Error:

LDAP search failed to return object : 0000208F: LdapErr: DSID-0C090AC0,
comment: Error processing name, data 0, v3839 at
/usr/share/koha/lib/C4/Auth_with_ldap.pm line 97.

Our conf file is set up like this:

 <useldapserver>1</useldapserver>
 <ldapserver id="ldapserver" listenref="ldapserver">
 <hostname>ldaps://ldap.azag.gov</hostname>
 <base>"OU=XX,DC=XXXX,DC=XXX"</base>
 <user>ldapauth</user><!-- DN, if not anonymous -->
 <pass>XXXXXX</pass>              <!-- password, if not anonymous -->
 <replicate>1</replicate>       <!-- add new users from LDAP to Koha
database -->
 <update>1</update>             <!-- update existing users in Koha database
-->
 <auth_by_bind>1</auth_by_bind> <!-- set to 1 to authenticate by binding
instead of password comparison, e.g., to use A$ -->
 <anonymous_bind>0</anonymous_bind>
 <principal_name>%s</principal_name>
 <mapping>             <!-- match koha SQL field names to your LDAP record
field names -->
 <userid is="sAMAccountName"></userid>
 <password is="userpassword"></password>
 <firstname is="givenname"></firstname>
      <surname is="sn"></surname>
 <branchcode is="">XXXX</branchcode>
 <categorycode is="">PT</categorycode>
 <email        is="mail"></email>
 </mapping>
 </ldapserver>

When logging in, we have to use "username at XXXX.XXX" instead of just
"username". However, our emails are formatted "firstname.lastname at XXXX.XXX".
I thought this might be the reason it's generating the error, but I'm not
sure how to change the config file to reflect that. Or if I need to change
the auth_with_ldap file.

Thanks,
Michael