ubuntu 16+pyhton3.5环境下运行失败

Traceback (most recent call last):
  File "/usr/local/bin/twchat", line 7, in <module>
    from TWchat import start
  File "/usr/local/lib/python3.5/dist-packages/TWchat/__init__.py", line 3, in <module>
    import gui as wegui
ImportError: No module named 'gui'

tkinter已经安装。