The SSN must be entered WITHOUT any dashes. The date of birth must be entered WITH slashes. The address and ZIP code (5 digits only) must match the return exactly. The AGI must be entered in whole numbers only WITHOUT the comma(s).
The IRS generates the message that it cannot determine eligibility for the payment when either the security information entered on the first page doesn’t match IRS records, or the information has been entered so many times that you get locked out of the system for 24 hours. For additional trouble shooting see the IRS’s FAQs here: https://www.irs.gov/coronavirus