Page 1 is about how to provide evidence for a JOINT SPONSOR not the original sponsor. If you DO NOT HAVE ONE, it may indicate that you may have checked a box saying you DID have one. Check for that.
It may also just be instructions because you have not proven the OS meets the poverty guidelines.
This is where you may have screwed up as these are the instructions for the ORIGINAL SPONSOR keeping in mind that it's generic:
"If you have submitted Form I-864, Affidavit of Support, from the petitioning sponsor. We are unable to process the I-864 because it has one or more deficiencies. In order for us to process your application further, you must:
Submit a completed and signed Form I-864, Affidavit of Support, from the petitioning sponsor. A valid
signature consists of any handwritten mark or sign made by an individual, and does not include
signatures created by a typewriter, word processor, stamp, auto-pen, or similar device."
ENSURE that the PEN used does not look like it was printed by a device.
An easy was to do that is to use a UNIQUE, thin pen to sign.
"All pages must be
present and of the latest edition date."
Missing pages is common. Double check.
There is a grace period for new forms. It states that on the forms page under edition date. You can look for it yourself and see that's likely not the issue.
"Provide the petitioning sponsor's Social Security Number on Form I-864."
Double check. Also, double-check it matches the proof of filing taxes and any other financial proofs.
"Provide a complete and correctly calculated household size for the petitioning sponsor on Form I-864."
At least this mistake is for certain. Ensure it is the only one.
"Submit a complete copy of the petitioning sponsor’s Federal income tax return, including all supporting
tax documents (W-2s, 1099s, Form 2555, and tax schedules) filed with the return, for the most recent tax
year."
Are you sure you submitted the correct RETURN Transcript? This section indicates either an error in form OR an error in transferring amounts to your I864 from your financial documents.
Is the OS employer or self employed? The difference between what income each can use is HUGE and always mistaken.
Is the tax return the only proof you submitted or did you over submit and submit other financial evidences and perhaps not put those amounts in the correct boxes?
A copy of your I864 coverletter showing what you submitted would be helpful for us to help you.