Mailchimp remote ping error code 90 (not exported by this server)

Hi

I have my Remote Pings set up for Mailchimp as follows:

http://us2.api.mailchimp.com/1.3/?method=listSubscribe

apikey=79-HIDDEN-us8
id= 8-HIDDEN-e
update_existing=true
send_welcome=true
email_address=%useremail%
double_optin=false

GET METHOD

In Mailchimp, it is not subscribing any new people at all.

In Membership, ping history shows this:

http://us2.api.mailchimp.com/1.3/?method=listSubscribe 200 - OK

{"error":"Method listSubscribeapikey=79-HIDDEN-us8 is not exported by this server","code":-90}

How can I fix this?

Thanks,

David