Date error on CoursePress Pro

I am playing around with CoursePress Pro to get it to do what I want. Now I am trying to make course units available in the future. But when I set a date in the future than when try and take the course as a student it says.
This unit will be available on 01/01/1970

Do I need to do something with the date format?
Or have I run into a bug that needs to be solved in a next release.

Hope to hear from you,
thx Han