Underpay penalty: Sum of the 4 qtrs adds up to the total withholding for the year. Federal review shows numbers don't add up and only shows 3/4 quarters on the form.

Filling out the withholding by quarter to calculate the underpayment penalty.  The sum of the 4 quarters I entered adds up to the total withholding for the year.  When I go to the Federal Review section it claims the numbers don't add up and only shows 3 out of 4 quarters on the form.  Is this a bug?