EILD problem

Hi,
last night I've tryed to EILD with a recorded voice I made which tells "This is a dream". I read that while dreaming, you should be able to hear any sound, and if I hear this voice reminding me I'm dreaming, I could become lucid.
Last night I set the alarm at 03:55, 04:00 and 04:05. It turned off automatically after 5 seconds. I calculated fine the REM period, infact I was dreaming in that moment. But I didn't hear the first two alarms insisde the dream, while I woke up when the third alarm went off, while I was still dreaming.
What am I doing wrong? If the alarm volume was too high because it woke me up the third time, why didn't I hear the first and the second one during the dream? Any suggestions?

I've tried this a couple times, but I either didn't hear it or, more often, it just woke me up. I don't remember where, but I recall reading that this is a pretty unreliable method due to things being distorted in dreams and also being unable to pick up on signals since your brain's logic center is not working during that time. So I guess maybe you could hear it and not even realize it!