After clicking on "Ping now", all are alright except for moreover which returns a 404.
So what should the preset address be, or how do I remove it from the list to be pinged, if it is permanently 404?

Here's the preset ping:
Ping: http://api.moreover.com/ping?u=http://www.covingtongallery.com/sitemap.xml ...
Response code: 404 - Not Found 404

A1Sitemap Generator version is 2.3.5 My OS is W-7.

Seems they have closed moreover pinging: http://api.moreover.com/ping
But I will be adding some other instead