User Nice Name instead of Username in remote pings


I'm setting up some php pages to send pings to Getresponse since I tested Membership but the syntax of the ping it sends to the api url is not correct.

Anyway I'm trying to send through the remote ping in Membership the chosen name (nice name instead of username) of the user, but if I use %usernicename% the plugin uses anyway the username (as with %username%).

I tried filling every field in Wordpress with different data to be sure (username, name, surname, etc.) but the pings always sends the username.

Should I change something somewhere?