Maybe it is debris left behind after removing the failed patch, but there seems to be some junk on the tube that would have been under the patch. I'm not saying this is why the patch failed, but having visible foreign objects under a patch certainly can't help.
As above:
1. Ensure whatever caused the puncture is removed
ii. Clean and lightly sand area around puncture
c. Apply a generous amount of patch cement and spread it thin over an area larger than the patch
IV. Allow the cement to dry, 5 minutes should be enough
5. Peel the foil backing off the patch and press firmly onto the dried cement on the tube, generally working from the centre of the patch out. You can use a rounded corner of the patch kit box to press the tube on extra hard.
If for some reason the patch does not work, you must be extra thorough in removing any leftover glue or debris before trying to re-patch.
I generally keep one or two known good tubes with me to install if I get a flat, and I patch the punctured tube when I get home and put that with my spares.
I had ~20 punctures last year (it was a bad year) and none were caused by failed patches. One was caused by a crease in a Park tire boot, though.