I am getting an error that a negative number is not a valid number for the date restriction. Wouldn't a negative number be a valid specification? How else would I set the date range to be only in the past?

Customer is trying to accomplish the following

Is there a way to set a rule on the birthdate calculator that if the year used is equal to or less 14 years (2007) that an error is given? Multiple employees input the right date and month but it defaults to the current year