Asterisk error: WARNING[xxxxx] app_voicemail.c: Failed to obtain database object for 'DATABASE_NAME'!

I received below error on /var/log/asterisk/message:

[2012-05-20 10:28:48] WARNING[12496] app_voicemail.c: Failed to obtain database object for 'DATABASE_NAME'!

[2012-05-20 10:28:48] WARNING[12496] app_voicemail.c: Failed to obtain database object for 'DATABASE_NAME'!

[2012-05-20 10:28:48] WARNING[12496] app_voicemail.c: Failed to obtain database object for 'DATABASE_NAME'!

to fix it we must add below lines to /etc/asterisk/res_odbc.conf

and below lines to /etc/odbc.ini

[ut_a2b]

dsn => DSN_NAME

pre-connect => yes

enabled => yes

[DSN_NAME]

Description=Asterisk voicemail odbc storage

Driver=MySQL

Server=SERVER_ADDRESS

User=DB_USER

Password=SOME_PASSWORD

Database=DB_NAME

Option=1

Trace=yes

Tracefile=/tmp/odbc.log