The problem is that MailChimp is designed to accept Mail List signups from sites like S.W.A.T. or TFL; but it is not designed to register you in the reverse direction. Confusing, I know; but it makes sense from a privacy standpoint.
You can Register at TFL and choose to enroll in the S.W.A.T. mail List; but that doesn't give us permission to set you up with an account at the S.W.A.T. Site. Just as you can sign up for an account at the S.W.A.T. site, but that doesn't give us the right to register you at TFL.
Finally, you can sign up for the S.W.A.T. Mail List without ever being a member of TFL or S.W.A.T.
Bottom line, in your case: You're a TFL Member who chose to enroll in the S.W.A.T. Mail List. While we'd love to have you become a Member at S.W.A.T. also, that's something you have to sign up for separately.
Now even I'm confused!