Most likely, that's because your input was incomplete or your client does not qualify.  Check that you have made the entries according to the instructions in this article and ensure your client met all the conditions:

https://proconnect.intuit.com/community/help-articles/help/how-to-generate-dependent-care-credit-for...

I found the answer for my own question.  I just need to check "diabled" box even if the qualifying dependent is not certified "disabled".  She is just unable to support herself.