Piwigo encountered a non recoverable error

[mysql error 1044] Access denied for user 'plainweb_piwi648'@'localhost' to database 'plainweb_piwi648'
Connection to server succeed, but it was impossible to connect to database

#1	my_error /home/plainweb/public_html/avrain.co.uk/gallery/include/common.inc.php(121)
#2	include_once /home/plainweb/public_html/avrain.co.uk/gallery/picture.php(25)