IFTTT SMS Channel didn't send an activation Pin code

Hey Guys
I tried to connect to SMS channel on the IFTTT but I didn’t receive any PIN code to my phone to connect properly. The issue happened when I tried to receive an SMS for each new event I publish from my device. I was connecting successfully to the SMS channel but when I made disconnect and reconnect again I couldn’t receive the PIN activation code. I’m using AT&T as a GSM carrier. Anyone has the same issue?
Thanks in advance.