How should I fix this error

[ChenShiTong-CN]

[ma-sadeghi]

Hi,
To be able to help you, your question needs to be well defined:

1. Come up with a descriptive title
2. Describe the issue in your own words
3. Produce and show a minimum working example (MWE*)

*An MWE is a short script that reproduces the issue you're having. It's NOT necessarily the script you've been working on, but a small subset of it. You need to spend some time for producing a good quality MWE as it helps developers help you more efficiently.

**A screenshot is not an MWE.