Maureen told me that when she went to use diapers.com, she had some problems with the coupon code working. I contacted them to make sure everything was ok with sending the diapers to the same address (provided it was a new customer) and they acted like it shouldn't be an issue. If you do have problems, and the coupon code does not take, they said to give them a call before hitting "submit" (they are super nice, and answer quickly)and they will force the coupon code through.
Their number is: 1-800-diapers
If you want to let me know how it worked for you, click here.