MacBook Pro mini displayport to DVI D doesn't show anything on the Compaq 2021 monitor I am using a MacBook Pro running 10.6.8. I have been using a Compaq s2021a monitor with mini displayport to VGA adaptor and cable until now. I bought a mini displayport to DVI adaptor and DVI - DVI cable and connected to the monitor. The laptop is detecting the display and allows me to change the resolution but nothing is seen on the display of the monitor. There is a flicker on the screen when the resolution is changed to 1024x768 when I click on the calibrate button. 

Can someone help me to resolve this?
If you were using vga before, the monitor may not take digital input. DVI-D is digital only. VGA is analogue. 

Try using a DVI-A or similar analogue signal.