trapped chests-pressure plates not triggering redstone

What I expect to happen: Placing a trapped chest or pressure plate over a redstone torch or redstone dust will propagate a signal that inverts the torch or generates a signal that travels along the dust trail.

what happens: nothing. I can see a weak redtone signal, like you would find at block 15 of a redstone wire if I use a trapped chest. pressure plates have no effect at all, but they do open iron doors.

Redstone has worked the way I am trying to use it since time immemorial.