请问大家这个错误是怎么回事呢

WIN7，安装了 VSCODE 和 Anaconda3，在用 VSCODE 开发时，一运行就报如下错误，恳请大家指点如何解决，感谢！

PS C:\Users\xx\AppData\Roaming\Code> cd 'C:\Users\xx\AppData\Roaming\Code'; ${env:PYTHONIOENCODING}='UTF-8'; ${env:PYTHONUNBUFFERED}='1'; & 'D:\Anaconda3\python.exe' 'C:\Users\xx\.vscode\extensions\ms-python.python-2018.2.1\pythonFiles\experimental\ptvsd_launcher.py' 'C:\Users\xx\AppData\Roaming\Code' '57419' '34806ad9-833a-4524-8cd6-18ca4aa74f14' 'RedirectOutput' 'c:\Users\xx\AppData\Roaming\Code\User\x\t1.py'
Traceback (most recent call last):
File "C:\Users\xx\.vscode\extensions\ms-python.python-2018.2.1\pythonFiles\experimental\ptvsd_launcher.py", line 76, in
import ptvsd
ModuleNotFoundError: No module named 'ptvsd'