Well...............
It's hard to say exactly what caused the plane to disappear when it landed at KJFK, but it is 
definitely one of two things:
The posted flight plan is problematic for two reasons.  First, the 2-hour interval doesn't allow the aircraft to complete the flight plan in the time alloted.  You might consider increasing the interval to 6 or 8 hours.  Second, the standing time at KJFK is ten minutes.  Most literature I have read about Traffic Tools recommends a minimum standing time of 30 minutes at the end of each leg of a flight plan.  Personally, I have used a standard minimum of 35 minutes in the plans I have created, with good results.  
The other possibility is that the aircraft you are using is not suitable for AI traffic use.  Personally, I am not aware of a Gulfstream IV that was designed for AI traffic use, but whenever I have a question about a particular aircraft, I always test it in a controlled environment before putting it into a flight plan.
If you get around to testing and discover that it works, please let me know!  I'd love to have that aircraft in my hangar!
By the way, I hope you received the AFCAD file I mailed you...... 
