Realtime with asterisk 1.4

hi guys , i have a2billing 1.4 with asterisk version 1.4 and asterisk-addons 1.4,and everything is working ok between a2b and asterisk and mysql connection is up and doing ok, i tried to enable realtime but i got this following errors at my cli :
WARNING[24680]: config.c:1335 find_engine: Realtime mapping for ‘sippeers’ found to engine ‘mysql’, but the engine is not available

this is my config :
-in res_mysql.conf

dbhost =
dbname = mya2billing
dbuser = a2billinguser
dbpass = a2billing
dbport = 3306
dbsock = /tmp/mysql.sock

-in extconfig.conf

sipusers => mysql,mya2billing,cc_sip_buddies
sippeers => mysql,mya2billing,cc_sip_buddies

iaxusers => mysql,mya2billing,cc_iax_buddies
iaxpeers => mysql,mya2billing,cc_iax_buddies


hostname = localhost
; port for postgres is 5432 by default
port =
user = a2billinguser
password = a2billing
dbname = mya2billing
dbtype = mysql

so is there any thing wrong with my config ?