Image doesn’t display on category / index view

Hello,

I’ve a weird problem with the display of my image. If you look at : http://sculpture-bronze-choisnet.com/blog/?p=20 you’ll see a picture in the post.
But if you look at http://sculpture-bronze-choisnet.com/blog/?cat=7 you’ll see the same post with no picture in it.

I’ve checked and my blog is set up to show entire post not summary. Any ideas ?