[Error]: Unknown option name [1month]

Stack Dump:

errorHandler(integer(256), string("Unknown option name [1month]"), string("/home/arthangout/public_html/lib/class.Main.php"), integer(15))
Main->CriticalError(string("Unknown option name [1month]"))
    [/home/arthangout/public_html/lib/class.ItemManager.php:90]

OptionManager->Get(string("1month"))
    [/home/arthangout/public_html/lib/class.ItemManager.php:20]

ItemManager->GetValue(string("1month"))
    [/home/arthangout/public_html/scheme.php:29]