and for information, i've installed the lime survey on a web server which is opensuse, and the DB is mysql but on an other server. I've tried deleting and reinstallin everything many times but i've got always the same issue on that particular server.
Since i've got an Ubuntu machine with mysql on it, i've tried making the installation on it and using the local host DB, and everything seems to be well. so i think the issue is with the Opensuse server may be apache or any other problem.