Reaver stuck with same error: "[!] WPS transaction failed (code: 0x04), re-trying last pin"

Question

[!] WPS transaction failed (code: 0x04), re-trying last pin is the only error that I get, and I get it all the time - reaver can't move forward! What's wrong? I'm using Mac OS 10.7.5

Here is the output:

[+] Trying pin "12345670"
[+] Sending authentication request
[+] Sending association request
[+] Associated with 5C:E3:0E:42:E1:BA (ESSID: ***)
[+] Sending EAPOL START request
[+] Received identity request
[+] Sending identity response
[+] Received M1 message
[+] Sending M2 message
[+] Received M1 message
[+] Received WSC NACK
[+] Sending WSC NACK
[!] WPS transaction failed (code: 0x04), re-trying last pin

Answer 1

use airodump-ng to see if wps is locked

sudo airodump-ng --wps wlan0

if its locked wait until it unlocks see if wps version is 2.0