Date Sorting in Excel PivotTables

I have a PivotTable that has a date field in it, call it Mydate.

I have put this as a column label and then grouped the label by Years, Months and Days.

I then have put the years and days in reverse order by clicking on the label and then choosing to Sort Newest to Oldest.

If I then expand the month to show the days and then try to sort the days, the sorting is messed up....it treats the days above 10 as coming before day 2, 3, etc.

Here is what it looks like in the row label section:

    -2015  
         -Apr
             9-Apr
             8-Apr
             ...
             2-Apr
             1-Apr
             16-Apr
             15-Apr
             ...

Is there any way to fix this in the PivotTable or do I need to make an additional "Day" column to get this to work properly?

EDIT: These are properly stored as dates and the sorting works properly if I Ungroup the date field and then sort on just the dates without Years or Months.