Transparency does not work?


i would like to use a transparent material on my object, but it does not seem to react to my settings. I tried with a cloud texture, the texture works, but the transparency still does not seem to work. Does someone know why?

the rendered image :

the material settings :


Shadows -> receive transparent.

Thanks, i don’t manage to get a good result, here are the pictures, would you have any idea?

the settings :