I really need help installing Kdenlive on my computer.

Hey guys! I am trying to install kdenlive on my Ubunu computer. Everytime I try to install it from Ubuntu Software Center it says:

This error could be caused by required additional software packages which are missing or not installable. Futhermore there could be a conflict between software packages which are not allowed to be installed at the same time.

And everytime I try to install it on my computer from the website I follow these steps:

Ubuntu Karmic 9.10 BETA

Kdenlive 0.7.5 packages are available at http://packages.ubuntu.com/karmic/kdenlive. OLD RELEASE, NO SUPPORT PROVIDED!
This version of Kdenlive is deprecated. It is strongly recommended to install Kdenlive 0.7.6 packages using sunab alternative repositories:

1. go to System Menu > Software Sources > Third-Party Software;
2. click add and paste this line in:
deb http://ppa.launchpad.net/sunab/ppa/ubuntu karmic main
3. close software source and click reload.

After adding the repository, you also need to add the key for the repository to your system's list of trusted keys, type the following command line in the terminal :
sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com B5115B98AA836CA8

Then click the reload button of synaptic and install Kdenlive package or type the following command line :
sudo apt-get update && sudo apt-get install kdenlive

Okay and when I do the first step it says there is an error and they it says:

Package dependencies cannot be resolved.
W: GPG error: http://ppa.launchpad.net karmic Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 52165BD6B9BA26FA
W: GPG error: http://deb.opera.com stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY F9A2F76A9D1A0061

I have been trying to work this out for a while. I really need help!!!

Thanks!