Ionic cordova run andorid -l error connection was unsuccessful

Ionic info:
cli packages: (C:\Users\Admin\AppData\Roaming\npm\node_modules)

@ionic/cli-utils  : 1.16.0
ionic (Ionic CLI) : 3.16.0

global packages:

cordova (Cordova CLI) : not installed

local packages:

@ionic/app-scripts : 3.0.1
Cordova Platforms  : android 6.3.0
Ionic Framework    : ionic-angular 3.8.0

System:

Node : v8.7.0
npm  : 5.5.1
OS   : Windows 10

Environment Variables:

ANDROID_HOME : not set

Misc:

backend : pro