TurboTax is computing the California Earned Income Credit based on information that you've entered in the program. If you don't qualify for the credit, you'll need to make corrections in TurboTax, based on whichever factor bars the credit. Without knowing this, we can't tell you how to make a correction.
See Check if you qualify for CalEITC on the Eligibility and credit information page to see the qualifications. There's also a very handy calculator on the Earned Income Tax Credit Calculator page. If the calculator indicates that you qualify, it's very likely you do.