Have you added the public key to your system as indicated here?: https://help.launchpad.net/Packaging/PPA#Adding%20a%20PPA%27s%20keys%20to%20your%20system
Have you added the public key to your system as indicated here?: /help.launchpad .net/Packaging/ PPA#Adding% 20a%20PPA% 27s%20keys% 20to%20your% 20system
https:/