and external display

When i have my macbook hooked up to my 20" dell lcd display and my macbook goes to sleep it doesnt turn the monitor off. the monitor acts as if nothing is connected to it and leaves on a screen saver type screen saying no dsub connected. My old dell laptop would put the monitor in standby when it was in sleep mode. is there a reason for this and is there a way i can set it up to where my macbook turns of the monitor?

try using the remote to wake up the macbook, or if u have a external keyboard or mouse pressing any button should work.

i dont want it to turn on. im talking about when im done using it the computer i want the computer to turn the display off/ put in standby. whent he laptop itself goes to sleep.

I don't have a DELL display, but have you tried looking in to the settings on the actual monitor itself and see if there is some energy settings you can change?