Ping Mailchimp Api Setup Driving Me Batty : P

I have tried for 4 hours now to make the ping to Mailchimp functionality work to add subscribers to my list.

I *think* I am using the right details and have looked at so many threads now I am at a loss as to why it isn't working at all.

My API records are showing no pings and I have no idea why.

I have tried the 1.3 api and the 2.0 api using both post and get.

I know my list ID is correct..
checked it in the MC dashboard...

I know my API is correct...
checked that also in the MC api.

My settings I am currently using appear below:

Ping URL :

Ping Data:

Would LOVE some help on this as it is stressing me out : P

Ok... I tried this to see what output I would get :

and i got this response :

This XML file does not appear to have any style information associated with it. The document tree is shown below.

<string>Unknown method "/"</string>

So this leads me to believe that the method is wrong ? and I have no idea what method to use...