How can Aetna say I am not disabled when clearly I am?

I currently have STD through Aetna. I have fought to get the benefits, fought to have state income taxes taken out (unsuccessfully), and now fighting to keep the disability since I made someone mad. I uploaded the whole state tax booklet including a letter from the state treasure office showing the income taxes are their responsibility. My diagnosis is terminal, and I have already qualified for Social Security Disability. Now, I am being told when the long term kicks in I may not qualify based on Aetna standards. How can they say I am not disabled when clearly I am?