CREATE TABLE table_29087004_2 (written_by VARCHAR(255), united_states_original_airdate VARCHAR(255), directed_by VARCHAR(255), canada_original_airdate VARCHAR(255))
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?
    
SQL: 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"