Xfce xfce4 on FreeBSD 11 shows blank grey screen

I have installed FreeBSD 11 along with xfce4
When I run startxfce4 a blank grey screen shows up without panel or icons or taskbar.
I ran it using startx by adding exec /usr/local/bin/xfce-session in the .xinitrc file. I still get the same result.

Thanks in advance
Session must be launched with startxfce4.

To have panel, icons and so on:

cp /usr/local/etc/xdg/xfce4/xinitrc ~/.xinitrc

It defines some environment variables.
Thank you olivierd,
I tried what you told me. But still got the same result. I forgot to mention I am running FreeBSD 11 on Virtualbox. Hope the information was helpful
Are you sure xfwm4 is installed? Sounds like you may be missing an actual window manager.

run pkg info | grep xfwm and if xfwm4 doesn't show up in the list, install it.