did you actually drill a pilot hole or just try to go screw directly into wood.
Onto the topic, the way I mount pvc is that I get small thin screws, Drill a big hole through the top part of the pipe, then the pilot hole through the bottom part and then the wood, drop the screw into the pipe and screw it into the wood. To sum it up, big whole on top, screw through bottom half of pvc into wood.