CREATE TABLE table_4171 ("Series #" FLOAT, "Production Code" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "United States Original Airdate" TEXT, "Canada Original Airdate" TEXT)

Who wrote the episode directed by Jos Humphrey that had an original Canadian air date that was unknown and a United States original air date of August 27, 2011?
SELECT "Written by" FROM table_4171 WHERE "Directed by" = 'Jos Humphrey' AND "Canada Original Airdate" = 'Unknown' AND "United States Original Airdate" = 'August 27, 2011'
SELECT "Written by" FROM "table_4171" WHERE "Canada Original Airdate" = 'Unknown' AND "Directed by" = 'Jos Humphrey' AND "United States Original Airdate" = 'August 27, 2011'