Run PW in subdirectory at nginx, but return 404?

[taoguang]

Now I add a PW on my domain. It runs OK.

Then I have a second demo PW running under /demo/ subdirectory.

and adding these code to nginx rewrite:

location /demo/ {
    try_files $uri $uri/ /demo/index.php?it=$uri&$args;
}

Then I access the subdirectory's homepage(/demo/) is OK, other page return a 404 error.

But I replaced the other cms to /demo/, It's really OK. Why?

How to fix these errors?