Error when logging sip users from mysql

hi, I’m new in using asterisk and I have some problems. actually, I’m using the 1.8.4.4 version of asterisk and the addons are embedded. So I have configured the res_config_mysql.conf file and the extconfig.conf file. … according a tutorial I’ve followed …
when I write in command line “realtime mysql status”, it shows that the connexion is successful. but when i want to load the sip users from the database, asterisk don’t show them (by “sip show peers command”) and when I want to log them in a softphone, asterisk displays:
res_config_mysql.c:333 realtime_mysql realtime:invalid database specified: asterisk (check res_mysql.conf)
I would be glad If someone could help me!!