Fidning the difference between two dates in Storyline 2.

Hello all, I've read several helpful threads here that have gotten me to this point but now I seem to be extremely stuck. I'm building a series of triggers and variables to direct new employees to a specific portion on the course based on how long they have been with company. I'm using this javascript to set the variable for the current date:

var currentTime = new Date()
 var month = currentTime.getMonth() + 1
 var day = currentTime.getDate()
 var year = currentTime.getFullYear()
 var dateString=month + "/" + day + "/" + year
 var player = GetPlayer();
 player.SetVar("SystemDate",dateString);

This triggers when the timeline for the slide starts. Then the employee enters their specific start date which adjust the StartDate variable using simple text entry box. Everything up to this point works perfectly but here's where we go off the rails. Next, I need to calculate the difference between the current SystemDate and the employees StartDate and populate the difference into another variable, Difference. I'm trying to use this script but I'm getting nothing out of it:

 

var player = GetPlayer();

var date1 = player.GetVar("SystemDate");

var date2 = player.GetVar("StartDate");

var diff = player.GetVar("Difference");

 

diff = Math.round(Math.abs((date2.getTime() - date1.getTime())/(oneDay)));

 var oneDay = 24*60*60*1000; // hours*minutes*seconds*milliseconds;

 player.SetVar("Difference", diff);

If I can get this final variable to adjust I'm golden. So in utter defeat I turn to my more knowledgeable colleagues. Any help would be greatly appreciated

 Sincerely,

Allen McInnish