Hi Errol,
Wow! This is an oft discussed topic in the rec.birds group and I have never heard of it failing so completely before.
What size pipe did you try and how long was it?
How was it defeated? Did they just wrap there paws around the pipe and shuck and pump their way to the top?
If the latter I think I would try a silicon polish on the PVC and make it extra slippery for awhile. Bumping up the diameter of the pipe should help too. Usually this is used for squirrels and maybe it needs to be larger in diameter to defeat raccoons.
I have also heard that a 5 gallon bucket (or similar item) turned upside down and suspended by its top works pretty well too. The critter tries to climb up the pipe support and ends up inside the bucket and/or the rim of it doesn't give them enough purchase to make it around the bucket.