CREATE TABLE table_29087004_2 (written_by VARCHAR2, united_states_original_airdate VARCHAR2, directed_by VARCHAR2, canada_original_airdate VARCHAR2)

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_29087004_2 WHERE directed_by = "Jos Humphrey" AND canada_original_airdate = "Unknown" AND united_states_original_airdate = "August 27, 2011"
SELECT "written_by" FROM "table_29087004_2" WHERE "August 27, 2011" = "united_states_original_airdate" AND "Jos Humphrey" = "directed_by" AND "Unknown" = "canada_original_airdate"