VNC black screen on Fedora 27 with mate desktop

Question

I recently try to set up vncserver for a local server with Fedora 27, mate desktop, and miniconda. But I keep getting black screen and a black dot instead of a cursor. After endless searching for solutions on Google, I feel devastated.

Does anyone know how to solve this problem? Thanks a lot!

Here's my xstartup file:

    #!/bin/sh
    unset SESSION_MANAGER
    unset DBUS_SESSION_BUS_ADDRESS
    #exec /etc/X11/xinit/xinitrc
    exec /usr/bin/mate-session

And here's the message in the log file:

    Sun Sep  9 10:43:04 2018
     VNCSConnST:  Server default pixel format depth 24 (32bpp) little-endian rgb888
     VNCSConnST:  Client pixel format depth 6 (8bpp) rgb222
    mate-session[20227]: Gtk-CRITICAL: gtk_main_quit: assertion 'main_loops != NULL' failed
    mate-session[20227]: CRITICAL: dbus_g_proxy_new_for_name: assertion 'connection != NULL' failed
    Gtk-Message: GtkDialog mapped without a transient parent. This is discouraged.
    mate-session[20227]: Gtk-CRITICAL: gtk_main_quit: assertion 'main_loops != NULL' failed
    mate-session[20227]: GLib-GObject-CRITICAL: g_object_unref: assertion 'G_IS_OBJECT (object)' failed
    mate-session[20227]: WARNING: Could not make bus activated clients aware of GTK_OVERLAY_SCROLLING=0 environment variable: Could not connect: Connect$
    mate-session[20227]: CRITICAL: error getting session bus: Failed to connect to socket /tmp/dbus-MBd4GHdrRv: Connection refused
    mate-session[20227]: WARNING: Unable to register presence with session bus
    mate-session[20227]: CRITICAL: dbus_g_proxy_new_for_name: assertion 'connection != NULL' failed
    mate-session[20227]: CRITICAL: error getting session bus: Failed to connect to socket /tmp/dbus-MBd4GHdrRv: Connection refused