The cache is not at the posted co-ordinates.
My geobuddy, FrodoB, thought I'd put red herrings in a couple of my recent puzzles. I hadn't, so I've created a special puzzle with herrings of various colours.
You can validate your puzzle solution with certitude.
[Puzzle] Erq Ureevatf? Jr qba'g arrq ab fgvaxva' erq ureevatf![Cache] pebgpu bs gerr, jvyq fvqr bs gur genvy