1) did you have /ps on
2) did you shift while placing it
Either way, they're already broken.
I'm going to assume that they worked before. But just in case, to prevent this:
1. Don't hold shift while placing it.
2. Don't use /ps off
And when you are in game, just type in "/helpop I need my PS's fixed" and an Operator+ will gladly assist you momentarily. Sorry for the inconvenience.