Import data format question

I have an excel file which I am importing data from. All data imports perfectly except my date and time fields. I have tried several date formats and can not get the data to import properly.
I have used

mm/dd/yyyy (format used in php runner application)

yyyy-mm-dd (mysql standard format for import of date field)
For time I am using h:mm AM/PM
All imported data shows dates of 0000-00-00 and times of 00:00:00.