but of course you already know nothing's getting there using the switch.
Generally, the wiring it not the problem. If you are sure there is no fuse that could account for this behavior (there is a fuse that controls my 996's spoiler and engine compartment lid so be aware these fuse and circuit assignments can be rather (to me anyhow) disorganized).
Thus I would hazard a WAG that if you would expose the switch and its wiring you'd probably see the problem. The switch to open the front trunk and the rear trunk look to be the same to me based on what I can see. If the switches can be easily swapped you can swap them and see if the non-operation symptom follows the switch.