CREATE TABLE table_56398 ("Home team" CLOB, "Home team score" CLOB, "Away team" CLOB, "Away team score" CLOB, "Venue" CLOB, "Crowd" FLOAT, "Date" CLOB)

When did the game with North Melbourne as the away team take place?
SELECT "Date" FROM table_56398 WHERE "Away team" = 'north melbourne'
SELECT "Date" FROM "table_56398" WHERE "Away team" = 'north melbourne'