PWM always at 100% duty cycle?

[Isaiah Zwick-Schachter]

I have a omega2+ with the power dock and the PWM expansion, but whenever I try and plug something into the PWM expansion (e.g. an led, a motor) it's always at full power, even when I set the duty cycle to 0%. The same happens if I use the Web UI and if I try and do it from the command line. Any suggestions? Is my PWM expansion broken?