Deductions & credits

I have found the entry that is causing the problem.  

In the section for your wife's business, the question "Did you play an active role in this business?" is marked "no".  Return to the section for Business Income and click edit.  Continue 4 or 5 screens in and look for this question (I pasted a screenshot of what it looks like below, for reference).

Change the "no" to "yes" and then click Continue (answering questions where required noting that some will require re-validation) until you get to the end.  

Once you've done this, return to the dependent care section again. 

You'll see it will ask a few more this time than it did initially, and at the end it should present you with a credit.