USB Keyboard Emulation on the Due

I'm trying to get the Due to send strings to the PC/USB emulating a Keyboard. Following the Mouse and Keyboard Libraries tutorial on the example - it works great on the Micro (same wiring and code as this example page). But when I try the same example on the Due, I get no response. According to the Mouse and Keyboard Libraries page, USB emulation works on the Due, Micro, or Leonardo. I'm using the Programming Port. I've tried the other port, not working either.

I wonder what's different on the Due for this Library? Any ideas?

If you go over to the Due forum you'll see there's a sticky thread listing libraries and
their status w.r.t. to the Due, worth a quick search there.

Thanks, good place to check. Meanwhile, I figured it out. I plugged my PC USB cable into the Native USB Port (instead of the programming port) and USB Keyboard Emulation works now.