FATAL ERROR DB Error: connect failed in freepbx 2.8.1 r13

Hello,

Whenever try to open freepbx page following error occurs.
FATAL ERROR

DB Error: connect failed

Trace Back

Array
(
[0] => Array
(
[file] => /var/www/html/admin/common/db_connect.php
[line] => 69
[function] => die_freepbx
[args] => Array
(
[0] => DB Error: connect failed
)

    )

[1] => Array
    (
        [file] => /var/www/html/admin/header.php
        [line] => 131
        [args] => Array
            (
                [0] => /var/www/html/admin/common/db_connect.php
            )

        [function] => require_once
    )

[2] => Array
    (
        [file] => /var/www/html/admin/config.php
        [line] => 54
        [args] => Array
            (
                [0] => /var/www/html/admin/header.php
            )

        [function] => include
    )

)

below is my config
Details of package versions
(Text Mode)
Name Package Name Version Release
Kernel
Linux(i386) 2.6.18 238.12.1.el5
Name Package Name Version Release
Elastix
elastix 2.2.0 23
elastix-im 2.2.0 2
elastix-system 2.2.0 17
elastix-my_extension 2.2.0 6
elastix-reports 2.2.0 10
elastix-a2billing 1.9.4 4
elastix-framework 2.2.0 25
elastix-callcenter 2.1.3 1
elastix-security 2.2.0 10
elastix-addons 2.2.0 9
elastix-firstboot 2.2.0 9
elastix-agenda 2.2.0 8
elastix-asterisk-sounds 1.2.3 1
elastix-email_admin 2.2.0 11
elastix-pbx 2.2.0 22
elastix-fax 2.2.0 6
elastix-extras 2.2.0 1
Name Package Name Version Release
RounCubeMail
RoundCubeMail 0.3.1 12
Name Package Name Version Release
Mail
postfix 2.3.3 2.3.el5_6
cyrus-imapd 2.3.7 12.el5_7.2
Name Package Name Version Release
IM
openfire 3.7.1 1
Name Package Name Version Release
FreePBX
freePBX 2.8.1 13
Name Package Name Version Release
Asterisk
asterisk 1.8.7.0 0
asterisk-perl 0.10 2
asterisk-addons 1.8.7.0 0
Name Package Name Version Release
FAX
hylafax 4.3.10 2rhel5
iaxmodem 1.2.0 1.1
Name Package Name Version Release
DRIVERS
dahdi 2.4.1.2 7
rhino 0.99.4 2.rc1
wanpipe-util 3.5.23 1

let me know further troubleshoot.