“Membership Payment/Join Page is not defined in the settings page.”
Sorry my bad, I did not have this filled in as I misinterpreted its purpose.
Aweber seems to have a way of intergrating 3rd party lists with an email parser and lists many 3rd party addons on the page. Unfortunately, WP eMember is not currently listed
“Integrate With Other Services”
“Easily integrate your list with many shopping carts and other third-party applications. “