Beginner Issue With Arduino Uno Prototype Shield - No Power

Hey,

I am trying to apply power to the protoshield for an Arduino Uno. The thing is that when I plug the USB port into the Arduino Uno, the power light in on (highlighted green). But as soon as I connect one side of the protoshield onto the Arduino Uno, the green power light turns off. What could be the reasons for this happening?

Thank you in advance for your advice.

Perhaps a short between power & ground? Try measuring resistance between the protosheield power & ground pins, should not see a real low resistance reading there, the USB can only supply 500mA of current.
Notice anything getting hot when you plug in?