Hi,
Thanks for your quick answer.
I tried to check all prerequisites (i modified max_input_vars=1000 is too small to 4000 in php.ini before installation but still the message..

)
Here the details :
PHP version is 5.4.24 : OK
Module PDO is available : OK
Module PDO for 'MYSQL' is available : OK
Module MYSQL is available : OK
Module MYSQLi is available : OK
Module MBSTRING is available : OK
GD Library is available and correctly installed : OK
Module IMAP is not available - impossible to configure ProjeQtOr to retreive notes from received emails
Module OPENSSL is not available - impossible to configure secured access to email server
Module XML is available : OK
max_input_vars=1000 is too small - value should be at least 2000, 4000 recommended - check your php configuration (php.ini)
max_execution_time=30 : OK
memory_limit=128M : OK
file_uploads=1 : OK
session.auto_start is disabled : OK
magic_quotes_gpc is disabled : OK
register_globals is disabled : OK
Database 'projeqtor' already exists : OK
Parameters are saved.