It looks like the problem is that you have defined the field as a 'Date and Time' field, when you really just wanted a 'date' field.
You can fix this by copying the App Group definition and making the change from date/time field to a date field before you save it. Once you set a field type, you can't change it.
Alternately, make sure the index data that you're trying to load contains date *and* time information - even if it's just zeros.
And of course, make sure that inside your Application Definition, you're using the right date field format - %m/%d/%y, etc.
Good luck!
-JD.