Problem to make piwik work : error

Hi,

I can’t make piwik work. I just have installed it in the
folder http://lg-proweb.fr/piwik to analyse my wordpress blog
http://trainingacademy-cheztoi.com (and others later)…

I exactly follow your official process to install piwik :
http://www.youtube.com/watch?v=sYPjFtCpcd4

It seems that the wp-piwik plugin I have installed on trainingacademy-chez.com is not working correctly. I have this error message written in red “une erreur s’est produite” in my plugin panel (I have joined files but it seems I can’t attach them here…).

Can you help me fix this problem.
Thanks in advance

Regards
Ludovic