It is your petition letter that was not well elicited and not well enough to answer all questions necessary to meet NIW criteria.
As suggested by GLU (glutamine? ), you need to invest on a good lawyer.
This is not an intent-to-deny letter. But if you don't answer well, they will send out an intent-to-deny letter later. One of my friend got this problem. Then he gave up and applied from a different category.