Trouble installing flatland

I followed the instruction for setup (prerequisite and stable realease), but this is what i get when i try running flatland-demo

(flatland-rl) root@LAPTOP-AOPAAUOQ:~# flatland-demo open_window - pyglet Traceback (most recent call last): File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/pyglet/__init__.py", line 378, in __getattr__ return getattr(self._module, name) AttributeError: 'NoneType' object has no attribute 'Window' During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/root/anaconda3/envs/flatland-rl/bin/flatland-demo", line 8, in <module> sys.exit(demo()) File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/click/core.py", line 1128, in __call__ return self.main(*args, **kwargs) File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/click/core.py", line 1053, in main rv = self.invoke(ctx) File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/click/core.py", line 1395, in invoke return ctx.invoke(self.callback, **ctx.params) File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/click/core.py", line 754, in invoke return __callback(*args, **kwargs) File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/flatland/cli.py", line 53, in demo show_predictions=False File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/flatland/utils/rendertools.py", line 63, in render_env show_predictions, show_rowcols, frames, episode, step, selected_agent, return_image) File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/flatland/utils/rendertools.py", line 533, in render_env return_image=return_image File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/flatland/utils/rendertools.py", line 761, in render_env_svg self.gl.show() File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/flatland/utils/graphics_pgl.py", line 56, in show self.open_window() File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/flatland/utils/graphics_pgl.py", line 24, in open_window self.window = pgl.window.Window(resizable=True, vsync=False, width=1200, height=800) File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/pyglet/__init__.py", line 384, in __getattr__ __import__(import_name) File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/pyglet/window/__init__.py", line 1896, in <module> gl._create_shadow_window() File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/pyglet/gl/__init__.py", line 208, in _create_shadow_window _shadow_window = Window(width=1, height=1, visible=False) File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/pyglet/window/xlib/__init__.py", line 166, in __init__ super(XlibWindow, self).__init__(*args, **kwargs) File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/pyglet/window/__init__.py", line 501, in __init__ display = get_platform().get_default_display() File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/pyglet/window/__init__.py", line 1845, in get_default_display return pyglet.canvas.get_display() File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/pyglet/canvas/__init__.py", line 82, in get_display return Display() File "/root/anaconda3/envs/flatland-rl/lib/python3.7/site-packages/pyglet/canvas/xlib.py", line 86, in __init__ raise NoSuchDisplayException('Cannot connect to "%s"' % name) pyglet.canvas.xlib.NoSuchDisplayException: Cannot connect to "None"