New LCD ACER 17

Question

I bought a new Acer 17 " Flat monitor to use with a 5 year old Dell Dimension 8250 Intel Pentium 4 Processor and when I hook it up all I get is a blank screen. I have a 64MB GeForce4 MX Graphics Card with TV-Out...I was told it should work if I have the same blue VGA video cable and I did but nothing comes up on the screen. I can hear Windows XP trying to open up on the speakers bu the screen doesn't show anything except white? What is my problem?