When we had our broadband installed the guy doing it took way too long and got very frustrated and made a mess of it, but it worked. Two days later it stopped working.
When the fault engineer came and fixed it, turned out the original engineer had connected us to the wrong cable, so when another engineer came to set up our neighbour's Internet, they disconnected ours.
But that doesn't mean anything if you can't measure it. It may as well not exist. How can you tell something is having a subjective experience? How can you tell if something is experiencing "qualia"? You can't.