ESP8266 -01 doesn't reply with anything
Hasn't the ESP8266 got different pin numbering? ie
arduino pin 2 = pin 4 on esp8266,
arduino pin 3 = pin 5 on esp8266,
and arduino pin 4 = pin 2 on esp8266? and pin 4 on esp8266 is the built-in led.
hope it helps.