Hiding a field based on the chosen date using conditions

I am having trouble getting a check box to remain hidden based on a birthday. I am using "today -21 years" but no mater what date I use it is displaying the check box?

It should be days and not years. So the "today -21 years" is incorrect. It should be "today -7665". The equation is 21(years) x 365(days in a year) = 7665 days. 

Here's the result:

Let us know if you need further assistance. Thank you.