Dependent Error on federal return

I am getting an error in my federal return.  In the Personal Worksheet, Part II, if I leave the box blank that I am not anyone's dependent, I get the error. I am single, 33 years of age and I am not a dependent of anyone else, nor do I qualify to be a dependent of anyone. Turbo Tax will not allow me to leave the box empty.  The amount I get back from federal increases if I leave this box blank, but decreases if I don't. I want to leave it blank.