setting up a hotkey

so i am using adobe after effects cs3, and im trying to set up a hotkey for the RAM preview (the default is numpad 0). ive been using the keyboard shortcuts in the system preferences menu, and i the shortcut i create even shows up beside "RAM Preview" in the menu of after effects (it goes "Composition > Preview > RAM Preview" (composition being the title of a drop down menu in the program)), but when i press the hotkey, the only thing that happens is "composition" lights up for a split second. then when i select "composition" and do the hotkey, it works. its just that if im using the mouse to move over to "composition" anyway, it kind of defeats the purpose of creating the hotkey

any suggestions? thanks

bump. dont have much time