e-newsletter doesn't let me edit templates

started editing the HTML of the template, did it about 4 times, each time get hit with this message:

Cheatin’ uh?
You are not allowed to customize the appearance of this site.

did 1 more test without editing any html, or including any html in the branding tab. Just did simple editing of the template and got the same message. Let me know about any workarounds!

Thanks!