function.mktime

Bonjour,
j'ai ce petit soucis et je n'arrive pas a saisir.
Si qqn pouvais m'aider merci :

Code:

Unkown error type mktime() [function.mktime]: It is not safe to rely on the system's timezone settings. Please use the date.timezone setting, the TZ environment variable or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'Europe/Paris' for '1.0/no DST' instead line: 187 file : calendar.class - PHP 5.1.2(WINNT)

et la ligne correspondante :

Citation:

$intPremierJour = date('w',mktime(0,0,0,$month,1,$year));