CREATE TABLE table_56399 ("Home team" TEXT, "Home team score" TEXT, "Away team" TEXT, "Away team score" TEXT, "Venue" TEXT, "Crowd" FLOAT, "Date" TEXT)

If the Away team was south melbourne what Date did they play?
SELECT "Date" FROM table_56399 WHERE "Away team" = 'south melbourne'
SELECT "Date" FROM "table_56399" WHERE "Away team" = 'south melbourne'