OSError: no file with expected extension

[mxg007]

teacher：
when I run show3d_ball.py,there is an error
Traceback (most recent call last):
File "C:/Users/123456/Desktop/PointNet/PointNet-master_pytorch_yanxp/utils/show3d_ball.py", line 23, in
dll=np.ctypeslib.load_library(os.path.join(BASE_DIR, 'render_balls_so'),'.')
File "F:\anaconda1\lib\site-packages\numpy\ctypeslib.py", line 155, in load_library
raise OSError("no file with expected extension")
OSError: no file with expected extension