[Exim] CRAM-MD5 authenticator problem

This is my authenticator:

fixed_cram:
        driver = cram_md5
        public_name = CRAM-MD5
        server_secret = ${lookup mysql{select password from users where username = '${quote_mysql:$1}'}{$value}fail}
        server_set_id = $1

When a user tried to authenticate using cram-md5, the following errors
are generated in the mainlog:

2003-09-01 07:00:25 fixed_cram authenticator failed for <ip> (something)
[ip]: 435 Unable to authenticate at present (set_id=user@???):
"${quote_mysql" is not a known operator (or a } is missing in a
variable reference)

2003-09-01 07:49:43 fixed_cram authenticator failed for <ip> (something)
[ip]: 535 Incorrect authentication data (set_id=user@???)


But I can't figure out why :-(
to my eye everything looks balanced, my other authenticators work fine!

--
Avleen Vig
Personal: www.silverwraith.com
Admin: [burbank.ca|hannibal.mo].us.asylumnet.org