Error in Federal Personal Worksheet

I am single and have no dependents. On the Federal "Personal Information Worksheet," it asks if can someone  (such as your parent claim you as a dependent) can claim me as a dependent.  In my case, no one can claim me as a dependent. if I leave the yes or no boxes unchecked, I get an error message and the refund increases greatly, which obviously is what I want. If I mark no, it diminishes greatly. Why can't I leave either box empty?