If you’re using UAW plugin in your WordPress MU/3.0+ blog, starting version 3.1.26 it supports multisite environment (ability to have individual settings for subdomain blogs). But initial release had a bug resulting in errors of missing config.php as well as

permission denied – your token does not match our records

To fix this error, open file article_mods.php and locate function uaw_add_article. In global declaration after $win add , $blog_id. Then locate line

$uaw_config_file = getcwd() . ($win == "" ? '/config.php' : '\\config.php');

and replace it with

if ($blog_id == '1') 
   {$uaw_config_file = getcwd() . ($win == "" ? '/config.php' : '\\config.php');}
else
   {$uaw_config_file = getcwd() . ($win == "" ? '/config_'.$blog_id.'.php' : '\\config_'.$blog_id.'.php');}

Upload modified file to you UAW plugin directory, overwriting the old one and you’re good to go