Problem installing midori browser

Starting with Karmic, adding the PPA and its key is as simple as:
   sudo add-apt-repository ppa:midori

You may also want to use the WebKit-team PPA:
     https://launchpad.net/~webkit-team/+archive/ppa
You can find unstable Midori versions at
    https://launchpad.net/~midori/+archive/midori-dev
 More info: https://launchpad.net/~midori/+archive/ubuntu/ppa
Press [ENTER] to continue or ctrl-c to cancel adding it

gpg: keyring `/tmp/tmpkmba61pn/secring.gpg' created
gpg: keyring `/tmp/tmpkmba61pn/pubring.gpg' created
gpg: requesting key A69241F1 from hkp server keyserver.ubuntu.com
gpg: /tmp/tmpkmba61pn/trustdb.gpg: trustdb created
gpg: key A69241F1: public key "Launchpad PPA for midori" imported
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
OK
W: Failed to fetch http://ppa.launchpad.net/immerrr-k/qtwebkit4-backport/ubuntu/dists/trusty/main/binary-amd64/Packages 404 Not Found

W: Failed to fetch http://ppa.launchpad.net/immerrr-k/qtwebkit4-backport/ubuntu/dists/trusty/main/binary-i386/Packages 404 Not Found

E: Some index files failed to download. They have been ignored, or old ones used instead.