Unknown column 'Date' in 'order clause'

(SELECT nEvoEventID as EventID, e.sName as Event, nDateTime, v.sName as Venue, sLocation, sSeatingChartSmall as MapLocation FROM tEvoEvents as e LEFT JOIN tEvoConfigurations as config ON e.nConfiguration = config.nEvoConfigurationID LEFT JOIN tEvoVenues as v ON e.nVenue = v.nEvoVenueID LEFT JOIN tEvoCategories as c ON e.nCategory = c.nEvoCategoryID WHERE nDateTime >= '1508218771' AND e.bStatus = 1 AND v.nEvoVenueID != '' AND c.nEvoCategoryID IN (73,74,75,76,77,140,142)) UNION (SELECT nEventID as EventID, events.sTitle as Event, nDateTime, venues.sTitle as Venue, CONCAT_WS(', ',sCity,sState) as sLocation, sVenueImage as MapLocation FROM tEvents as events LEFT JOIN tVenues as venues ON events.nVenueID = venues.nVenueID LEFT JOIN tEventCategories as categories ON events.nEventCategoryID = categories.nEventCategoryID WHERE nDateTime >= '1508218771' AND events.bStatus = 1 AND events.bDeleted = 0 AND categories.sCategory NOT IN ("Sport","Concert","Theatre")) ORDER BY Date asc, Time asc LIMIT 0,20