The SNAP program takes into account those included in your household, not just your income. That could be a reason you were not approved.

There is also a formula that factors in rental and utility costs as well as transportation and medical costs and does or does not grant a standard deduction from your gross income to count toward the total against approval or denial. It is not a terribly complex calculation but there are a few variables. It can vary state to state and often the actual formula will be available somewhere on the DHS state website.