I am filing 2019 Tax return using TurboTax software.  For Child and Dependent Care Credit deduction , Turbo Tax shows my credit Percentage is 0%.  WHY? 

According to https://www.irs.gov/pub/irs-pdf/p503.pdf, the percentage ranges should be from 20% to 35%. So I should get miminum 20% percentage of Child care expense as Child and Dependent Care Credit (no matter how much income I have).   But Turbo Tax only gives me 0% percentage.  Is it a software bug?