If you're getting enrolled as Teacher it does mean that the account you're using is not the Site Admin account. I'm pretty sure of that.
You cannot login as a Site Administrator via LDAP authentication. The Site Admin user has to be a local user account. If you're logging in to a user account that is LDAP authenticted then it's not the site admin. That's just how Moodle works. To retrieve the site admin password (I often forget passwords for old moodle installs) you can use [Yes, help me login] button and enter the email address you used when you set the site up. The system will send you the username you used and invite you to reset the password. Try it out and see what happens -- it may help.