AVTAR with Active Directory user account

Hello,
What is the syntax to use an Active Directory user with avtar ?
For example user1@ad-domain.com ? (ad-domain.com as ActiveDirectory/LDAP domain)
"--id=user1@ad-domain.com" seems to be interpreted as user1 in avamar domain ad-domain.com not in the Active Directory domain ad-domain.com

I get the error message below :
avtar FATAL <5704>: Fatal Server Error occurred (MSG_ERR_DOMAIN_NOT_FOUND), aborting execution (MSG_CMD_SEARCH=135 serial=1 seq=0 flags=RU:N:0 kind=0 rsp=MSG_ERR_DOMAIN_NOT_FOUND)

Best Regards,
Didier