Are you sure you're looking at line 18a and not line 13a?
The $500 is the "Other Dependent Credit", for those who's child is too old (or otherwise doesn't qualify) for the Child Tax Credit. It's new, stating in 2018. It is unrelated to the EITC. The credit for Other dependents shows on line 13a of form 1040. Any EITC will be on line 18a. Your line 18a is probably blank.
