Enabling Android as USB host on Galaxy Nexus or Nexus 10

I'm trying to develop applications that talk to USB devices, but nothing works. I installed a USB Host Diagnostics app, and it tells me that there's no OS support for device detection on the Galaxy Nexus or the Nexus 10. I'm running Android 4.2 on both. I tried the AdbTest sample application, but that doesn't respond when I connect the devices together. I tried updating the files in /system/etc/permissions as discussed [here](https://stackoverflow.com/questions/11183792/android-usb-host-and-hidden-devices) , but that doesn't do anything. Can anyone get USB device detection to work on these devices? Thanks!