Cocos2dx version 3.9 using eclipe build error

cocos2d-x
1

Hello every one.
I’ve download the cocos2dx version 3.9 and create a Test project.
I using eclipe JUNO to open the android project and build.
I’ve got the following error.

  1. Description Resource Path Location Type
    Cocos2dxActivity cannot be resolved to a type AppActivity.java /Test/src/org/cocos2dx/cpp line 31 Java Problem

  2. Description Resource Path Location Type
    The import org.cocos2dx.lib cannot be resolved AppActivity.java /Test/src/org/cocos2dx/cpp line 29 Java Problem

I see the project already Linksource to the platform/android/java/src

And i try to using cocos command to compile, it said Running command: compile
Building mode: debug
19 is not a valid android target platform.

Please give me some guide.