I am trying to do a simple volume rendering on a ramses cosmological output by 

following the simple recipe that yt provides, but I get an AMRKDTree error. 

Can I not volume render a ramses output? I am using the latest version of YT. 

here is my simple code that fails:

ds=yt.load(filename)

sc = yt.create_scene(ds, field=('gas', 'density'))

sc.camera.resolution = (1024, 1024)

sc.camera.focus = ds.arr([0.3, 0.3, 0.3], 'unitary')

sc.camera.position = ds.arr([0, 0, 0], 'unitary')

sc.render()

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