Not sure when you ordered yours ( time of day ?? ), but did you receive a confirmation email from them for all three of the ones you ordered.
Even though you fill out the form , register and submit info and it tells you thanks.
They might have had 350,000 people who already registered before you already .
If you were in the first 250,000 they would have sent you an email confirmation telling you that you were and that your coupon will be there in 6 weeks.

Also you only have 5 minutes to fill out the form and it did state that if you took longer than that that you submission would not count.

You can register any day all day long , but to get the coupon you need to register after 9am EST on Friday only to be eligible.

Don't know why you didn't get yours , only giving you a few reasons why you might not have.

If you haven't received an email verifying your getting a coupon ,then you didn't win one and I would try again .

I received all 4 of mine already and ordered between 9 am - 9:05 am EST on Friday mornings .