vnc viewer not working--black screen

I followed the instructions on the udoo docs to set up a remote desktop using VNC. I downloaded VNC viewer for my mac, plugged the udoo neo using a usb cable to it, and typed in 192.168.7.2 in vnc viewer. It went to the authentication screen, i put in "udooer" as the password and then it goes to a black screen.

The board boots properly, and i can access the IP from the web. Can someone please help?

 

What happens if you plug in a monitor, do you see a desktop?

 

i plugged it into a monitor yesterday, and it worked perfectly. Later that night I downloaded VNC viewer and the black screen came up. This morning, I plugged it into my TV using the same cable and saw a black screen. I've plugged it into the TV and it has worked before.