Metasploit can't connect to database automatically at start up

To the point. Check my metasploit console.

=[ metasploit v4.10.0-2014082101 [core:4.10.0.pre.2014082101 api:1.0.0]] + -- --=[ 1331 exploits - 722 auxiliary - 214 post        ] + -- --=[ 340 payloads - 35 encoders - 8 nops             ] + -- --=[ Free Metasploit Pro trial: http://r-7.co/trymsp ]

msf > db_status
[*] postgresql selected, no connection
msf > db_connect -y /opt/framework/config/database.yml
msf > db_status
[*] postgresql connected to msf3

Why metasploit can't automatically connect to database when start up? Is there anyway to fix this? Thanks before.

By : root@Hades