Thanks for the replies.
The dimple dies I'm using are Avery's spring back so I think they are innocent!
Unfortunately at the moment I'm unable to send picture because my camera is at repair shop, I'll provide as soon as possible if I don't find a solution in the meanwhile.
Yesterday I dimpled the hinge of the tool box and it came out with a nice U shape @##!!@! Once clecoed to the body of the tool box there was no more problem, but I would like not to see a similar occurence on my empennage.
I looked at a lot of RV project around the web and never seen a piece warped like the one on my tool box... I'm really depressed!
I'll re-check the alignment of the DRDT... maybe it is not perfectly square...
