Thanks for your answers Rick and Ziad,

Concerning the update, unfortunately i cannot do that right now: the afni ver I use is on a network of computers and I need the administrator help to do that and he is not available for the moment.

Nevertheless, it seems indeed that the problems I'm facing are due to some bugs that could be solved by an update: I understood that things go wrong in suma (misregistration between surfaces and statistics) when I'm asking to view both hemispheres at the same time AND loading a dataset for the RIGHT hemisphere. But everything is correct if I'm asking for the LEFT hemisphere dataset or if I'm viewing one hemisphere only.
So for now I'm able to continue and get around the bug by always loading first the left hemisphere dataset!!

I will do the update as soon as possible and let you know if I still have some problem.

In the meantime could you indicate me which command I can use to make an average surface from all the standard surfaces of my subjects (like in the Fig 2 of your paper, Brenna D. Argall et al. 2006 in Hum Brain Mapp).I saw in the suma.pdf that we can
use 1deval to make some means (correct?), but then which files we have to average?

Thanks by advance.
Alain