DELL INSPIRON N4010 UNABLE TO CONNECT TO EXTERNAL MONITOR

Hi -
I have an Inspiron N4010 running Windows 7 Home Premium 64-bit.
I am trying to connect my laptop to an external display (Dell Ultrasharp 1704) via VGA.
For some reason, the monitor keeps turning on and off when connected to the laptop, and I see no video at all.
My laptop LCD is fully functional.

I have the latest Intel Display Driver.
In this, I set the optimum value for both the laptop LCD (1366 x 768 @ 60 Hz), and for the monitor (1280 x 1024 @ 60 Hz).
Still nothing.

What could be going wrong? How do I resolve this problem?

Thank you.