tigervnc on centos - black screen

I am running tigervnc-server on CentOS 6.8, however the gnome desktop won't start for me! I have done a yum groupinstall of "X Window System", "Desktop" and "General Purpose Desktop". On one of my other CentOS VMs (v6.6), installing these packages is sufficient for having the gnome-desktop automatically startup for me when starting a vncserver. I'm running: vncserver :05 -geometry 2048x1024 In /home/user/.vnc/hostname:05.log, I see: vncconfig: unable to open display "hostname:05" xrdb: Connection refused xrdb: Can't open display 'hostname:05' xmodmap: unable to open display 'hostname:05' ** (gnome-session:12313):WARNING **: Cannot open display The VNC server starts, and I'm able to connect via vncviewer, but get a black screen. Is there anything else I can look at to troubleshoot? The log isn't very helpful; I've been googling this problem for days, and haven't found anything that fixes it (Ex: made sure I'm in runlevel 5, I re-installed the desktop packages mentioned above, removed .vnc directory, stepped through xstartup, tried comparing various settings with my other VM where the gnome desktop is working) Anyone know of something else I can look at to troubleshoot this issue? Any other logs, or things to check?