Picture distortion

I'm quite new, not only on Kdenlive but on Video Edition too. So, my question seems to be very basic.

My computer screen is configured as 1280x800, I defined a project with the same resolution, a pixel ratio 8/5 and a screen ratio 8/5.
Then I add a clip, which is just a picture, with the same dimensions (8:5) but the picture I see on the monitor is made narrower, distorted. I see the shapes enlarged and tighter inside a wider black frame.

What is wrong here?
I would appreciate any help. Thanks in advance.

Maybe I had to add the software I'm using:
Fedore 16
KDE 4.8.3

Not too sure about this, but I know the first thing I would try. In the Project tree, double click on the image and in the clip properties click on advanced. Now check the box "force aspect ratio". See if that helps.

Thanks for your help.
Changing that ratio I got it.
The strange thing is that it takes the full screen, without distortion apparently, forcing a 23:9 ratio (~12,8:5) which is far from my 8:5 screen.

Well, my mistake came from a misunderstand of 'Pixel Ratio'. I put 8:5 while 8:5 was the screen ratio.
So, putting 1:1 as Pixel Ratio everything works well.
Thanks, normcross, for your help