Installed Percona-Toolkit, but no sign of xtrabackup

I've installed Percona-Toolkit on my Debian (Wheezy) test Server, using

dpkg -i percona-toolkit.deb
apt-get install --fix-missing -f
dpkg -i percona-toolkit.deb

However, there is no sign of Innobackupex in the /usr/bin folder. Trying to run it simply gives me Command Not Found

I can see all the pt-xxx applications in there suggesting the installation worked ok.

I then tried

apt-key adv --keyserver keys.gnupg.net --recv-keys 1C4CBDCDCD2EFD2A

as per the documentation, but that resulted in:

. . .
gpgkeys: key 1C4CBDCDCD2EFD2A not found on keyserver    
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0

Followed by

apt-get install xtrabackup

But that gave me

Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package xtrabackup

How can I get xtrabackup (Innobackupex) installed as well?