Determine if end date is after start date

I have 2 date fields on a form.  When I click the submit button I am trying to make sure the end date is after the start date.

Here is the code I am using:

      var eDate = Date.parse(BackgroundInformation.Background.CheckingDateEnd.rawValue);

      xfa.host.messageBox("Start Date:" + BackgroundInformation.Background.CheckingDateStart.rawValue);

      xfa.host.messageBox("eDate:"+eDate+" sDate:"+sDate);

      if(sDate > eDate)

The message box shows the start date as 2014-10-30 but sDate is Nan.

I have tried:

      var sDate = new Date(BackgroundInformation.Background.CheckingDateStart.rawValue);

and when I display sDate is says "Invalid Date"

Any ideas?