TurboTax 2018."The amount you are claiming for medical expenses paid for dependants other than your spouse or minor children exceeds the total medical expenses."

When using TurboTax CD/download you will need to enter as follows- Enter all your families medical expenses together- then the next page you will see the following "Dependent medical expenses"  which will list your child or children over 18 years of age. Then you will enter the amount of medical expenses you claimed for them.  This should fix the issue.