Power Button on Apple 27" Monitor Won't Start new Mac Pro

Since my switch from a G5 to a Mac Pro, the power button on my 27" three leg acrylic monitor no longer starts up my Mac. I now have a power block for the monitor with an adaptor that includes a USB plug. I have plugged the USB plug into one of the available ports, but the power button on the monitor still doesn't start the Mac Pro. Is there anything I can do to get it to work like it used to?