The following language strings are missing from:
modules/Orders/lang/en_US.php

dateopt_thismonth
dateopt_thisquarter
dateopt_thisyear

# D
$lang['date'] = 'Date';
$lang['date_range'] = 'Date Range';
$lang['dateopt_exactdates'] = 'Exact Dates';
$lang['dateopt_7days'] = 'Last 7 Days';
$lang['dateopt_14days'] = 'Last 14 Days';
$lang['dateopt_30days'] = 'Last 30 Days';
$lang['dateopt_3months'] = 'Last 3 Months';
$lang['dateopt_6months'] = 'Last 6 Months';
$lang['dateopt_1year'] = 'Last Year';


These are called from: "/modules/Orders/function.admin_reports_tab.php"

$date_opts = array();
$date_opts['exact_dates'] = $this->Lang('dateopt_exactdates');
$date_opts['7days'] = $this->Lang('dateopt_7days');
$date_opts['14days'] = $this->Lang('dateopt_14days');
$date_opts['thismonth'] = $this->Lang('dateopt_thismonth');
$date_opts['30days'] = $this->Lang('dateopt_30days');
$date_opts['thisquarter'] = $this->Lang('dateopt_thisquarter');
$date_opts['3months'] = $this->Lang('dateopt_3months');
$date_opts['6months'] = $this->Lang('dateopt_6months');
$date_opts['thisyear'] = $this->Lang('dateopts_thisyear');
$date_opts['1year'] = $this->Lang('dateopt_1year');