[1.0]Why my drone not trigger build?

I have install drone on a single machine follow the documentation, and I add a simple golang repository.

package main
import "fmt"

func main(){
	fmt.Println("ad1212fasd")
}

In the repository, there has one main go param,
and I add a .drone.yml file for the repository, like this

kind: pipeline
name: default

steps:
  - name: backend
    image: golang
    commands:
      - go build

but the drone serve doesn’t trigger the build

Is there anything wrong?

We have a thread that can help you debug this. See Nothing happens when I push code, no builds, or builds stuck in pending