What was round of 64 of the singles event when the result of round 16 was did not advance and the athlete was Iveta Benešová?
create table table_17289604_38 (round_of_64 varchar, athlete varchar, event varchar, round_of_16 varchar, PRIMARY KEY (round_of_64))
select round_of_64 from table_17289604_38 where event = "singles" and round_of_16 = "did not advance" and athlete = "iveta benešová"