How to set appropriate categories page

[Wanyuxiang-code]

I have attached category labels in the frontmatter of my markdown filers, and I have enabled the navigation bars, but Jekyll seems can't generate appropriate labels, and the categories are just empty. I don't whether it is because my traditional _posts directory has been named "_notes" as a git subdirectory.



I have been troubled for a few days, it will be highly appreciated for your warm-hearted help.
Thanks & Regard