Database connection failed!

Stack Trace:

File: /mnt/www/sigs/ojs/classes/core/Application.inc.php line 29
Function: PKPApplication->PKPApplication()

File: /mnt/www/sigs/ojs/lib/pkp/includes/bootstrap.inc.php line 58
Function: Application->Application()

File: /mnt/www/sigs/ojs/index.php line 61
Function: require("/mnt/www/sigs/ojs/lib/pkp/includes/bootstrap.inc.php")