You received a rejection email that we cannot see. Please tell us word for word what it says so we know how to help you.
You mean they need a 2018 AGI?
Where do I find my AGI?
Your 2018 tax return shows your 2018 Adjusted Gross Income (AGI) If you filed a joint return then the AGI is the same for each of you.
Form 1040 line 7
If you are using the same TT account that you used last year, you should also be able to find this number in your Tax Home for 2018