Are you married? Maybe the home office is under your spouse's name?
If you are not showing a loss on Schedule C.
Some expenses, such as home office or section 179 depreciation can only be used to reduce your schedule C taxable income to zero, and not to create a loss. Excess deductions for these carry over to the next year. And you have to answer yes to both questions about exclusive and regular use, not just one. The area of your home office must be used regularly and exclusively for business to deduct it.
Or you checked the box on 32b saying Some Investment is Not at Risk.
If you have money not at risk you can not take a loss on schedule C. If you don't know what it means then probably All your Investment is at Risk (check Box 32a). It means you are using your own money for the business. People usually check the wrong box.
can you check form 8829. That's where the HO deduction is calculated.
When it asks you how much of your income was earned from the Home Office, saying less than 100% causes that problem (it often causes line 8 of Form 8829 to become negative).
Personally, I think it is an error in the law, but unfortunately, that is how the law is written. Although some people think a person should say 100% in all circumstances (unless they have multiple offices), but my first inclination is that isn't right.