isNodeOccupied issue

[boazMgm]

Hi,
I'm running this simple test (after I've initialized the Octree):

test_point = np.array([1.0, 2.0, 3.0])
node = tree.search(test_point)
occupancy = tree.isNodeOccupied(node)

And I get the following error:
File "octomap/octomap.pyx", line 461, in octomap.OcTree.isNodeOccupied
octomap.NullPointerException

Do you know what might be the issue?
Thanks