I am having trouble adding the PPA key in Ubuntu.

I followed the info given on this page https://launchpad.net/~team-xbmc/+archive/ppa and executed this command.

"sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 91E7EE5E"

and following is the output I got.

Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --secret-keyring /etc/apt/secring.gpg --trustdb-name /etc/apt/trustdb.gpg --keyring /etc/apt/trusted.gpg --keyserver keyserver.ubuntu.com --recv-keys 91E7EE5E
gpg: requesting key 91E7EE5E from hkp server keyserver.ubuntu.com
gpgkeys: key 91E7EE5E not found on keyserver
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0

I am probably wrong somewhere. Could someone please point it out??