can not access to database in moodle

I am using moodle and I change location of my web site, but I am facing this error.

My config.php is:

<?php  /// Moodle Configuration File 

unset($CFG);

$CFG->dbtype    = 'mysql';
$CFG->dbhost    = 'localhost';
$CFG->dbname    = 'lightsys_test';
$CFG->dbuser    = 'lightsys_test';
$CFG->dbpass    = '123456a';
$CFG->dbpersist =  false;
$CFG->prefix    = 'mdl_';

$CFG->wwwroot   = 'http://www.lightsystem.ir/aya/moodle';

$CFG->dirroot   = '/home/lightsys/public_html/aya/moodle';
$CFG->dataroot  = '/home/lightsys/public_html/aya/moodledata';
$CFG->admin     = 'admin';

$CFG->directorypermissions = 00777;  // try 02777 on a server in Safe Mode

require_once("$CFG->dirroot/lib/setup.php");
// MAKE SURE WHEN YOU EDIT THIS FILE THAT THERE ARE NO SPACES, BLANK LINES,
// RETURNS, OR ANYTHING ELSE AFTER THE TWO CHARACTERS ON THE NEXT LINE.
// /home/lightsys/public_html/aya/moodle/
?>

And my error is:

Error: Database connection failed.

It is possible that the database is overloaded or otherwise not running properly.

The site administrator should also check that the database details have been correctly specified in config.php

Answer

Thanks to everyone.

My problem is solved. I had not set the right permission to my database, for my user, and when I did it my problem was solved.