我下载了Graphviz 2.38 MSI版本，安装在C:\Python34文件夹下，然后运行pip安装Graphviz，一切顺利。在系统路径中我添加了C:\Python34\bin。当我试图运行一个测试脚本，在行filename= .render(filename='test')，我得到了一个消息

 RuntimeError: failed to execute ['dot', '-Tpdf', '-O', 'test'], make sure the Graphviz executables are on your systems' path

我尝试将“C:\Python34\bin\dot.exe”放在系统路径中，但它不起作用，我甚至创建了一个新的环境变量“GRAPHVIZ_DOT”，其值为“C:\Python34\bin\dot.exe”，仍然不起作用。我尝试卸载Graphviz和pip uninstall Graphviz，然后重新安装它和pip install，但没有任何工作。

整个回溯消息是:

Traceback (most recent call last):
  File "C:\Python34\lib\site-packages\graphviz\files.py", line 220, in render
    proc = subprocess.Popen(cmd, startupinfo=STARTUPINFO)
  File "C:\Python34\lib\subprocess.py", line 859, in __init__
    restore_signals, start_new_session)
  File "C:\Python34\lib\subprocess.py", line 1112, in _execute_child
    startupinfo)
FileNotFoundError: [WinError 2] The system cannot find the file specified

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\Documents\Kissmetrics\curves and lines\eventNodes.py", line 56, in <module>
    filename=dot.render(filename='test')
  File "C:\Python34\lib\site-packages\graphviz\files.py", line 225, in render
    'are on your systems\' path' % cmd)
RuntimeError: failed to execute ['dot', '-Tpdf', '-O', 'test'], make sure the Graphviz executables are on your systems' path

有人有经验吗?