How to Multiple Monitors on D610

I recently got a Latitude D610 with a docking station and dell monitor. I like to extend my display to the external monitor to increse my viewing area, but the D610 doesn't allow me to do this.

 

When I got to display properties/settings and "attach" the second monitor, and then check the  "identity" both the laptop and the external monitor are display "1"

 

I've tried changing which monitor is the primary etc. but I can never get the computer to accept the external attached monitor. every time I click "Apply" the external monitor get un-attached....

 

Any idea how to fix this??

 

I'm thinking I might need a better display driver, but I don't know if there is one, or where to get it...

 

Thanks,