For the last 4 years, my self-employed wife did work at home, using part of our home. For the last 3 yrs, TurboTax has said we can't take the home office deduction. Why?

The space where my wife works at home is used only for her business. I have asked an accountant and was told we should have qualified for this deduction. My wife works 60 hours a week and spends about 30 hours working in her home office.