Hi, I have an XPS 13 laptop.  I just got a new Dell 21.5 Monitor (ST222) and when I connect it to the laptop, it will not allow me to have a dual monitor display.  I was connected to an older Delll monitor and had no problem. This is frustrating as I have frequently had this problem when I connect to a projector, but never with a monitor before. . Our office has four different projectors and I can only use dual monitors on one of them.  I connect to the projector using a standard VGA connection and a Dell purchased VGA adaptor.  I connect to the Dell monitor in the office using a  Display Link Docking Station and Dell provided VGA connection cable.