Pinhole Camera Fail :-(

Today is World Pinhole Day! And I got a pinhole camera kit for Christmas so decided that today was the day to try it out. However... all three of my attempts came out completely overexposed – entirely black negatives :-(

I followed the instructions to the letter too. The troubleshooting manual said that the three possibilities are: 1. overlong exposures (nope – I did 15-30 seconds each time), 2. a light leak in the camera (nope – checked it all around, and I'd have thought a light leak would have led to a dark patch, not 100% black), and 3. the photo paper having been exposed to white light... well I only handled the paper in the darkroom under a red safe light... so unless my safe light wasn't so safe, I'm wondering if there's a problem with the paper...?

Any pinhole experts care to comment?!