Hi everyone !

Thank you all for your concern and your help... It finally worked !

I got tired and confused in all this mess so I decided to create a new scene and it worked perfectly. I think the problem was regarding the normals of my object that I might have (by mistake) messed up...

Thank you all once again ! I guess the lesson here is : When you get yourself trapped... Re start from scratch... A little time spent for a lot of time saved.

++