I am attempting to connect a second monitor to my Inspiron 1520 laptop. When I plug the monitor in nothing happens. The display settings says that there is one monitor, the default monitor. The properties doesn't come up, the 2nd monitor option with 1 & 2 boxes does not come up. The monitor says no signal. Is there something that I need to turn on? The instruction manual says that the monitor is set up for dual monitors so I know that it can.