android – multiproject gradle build error：包不存在

App/
    settings.gradle
    app/
        build.gradle
    libraries/
        Core(git submodule)/
            Core/
                build.gradle
            libraries/
                ZBarLibrary/
                    build.gradle
            settings.gradle

应用/ settings.gradle

include ':App',':libraries:Core',':libraries:ZBarLibrary'
project(':libraries:Core').projectDir = new File(settingsDir,'libraries/Core/Core')
project(':libraries:ZBarLibrary').projectDir = new File(settingsDir,'libraries/Core/libraries/ZBarLibrary')

应用程序/应用/的build.gradle

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.5.+'
    }
}
apply plugin: 'android'

repositories {
    mavenCentral()
}

android {
    compileSdkVersion 17
    buildToolsversion "17.0.0"

    defaultConfig {
        minSdkVersion 14
        targetSdkVersion 16
    }
}

dependencies {
    compile 'com.android.support:support-v4:18.0.0'
    compile project(':libraries:Core')
}

应用程序/库/核心/核心/的build.gradle

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.5.+'
    }
}
apply plugin: 'android'

repositories {
    mavenCentral()
}

dependencies {
    instrumentTestCompile "junit:junit:4.5+"
    compile project(':libraries:ZBarLibrary')
    compile filetree(dir: 'libs',include: '*.jar')

}

android {
    compileSdkVersion 17
    buildToolsversion "17.0.0"

    defaultConfig {
        minSdkVersion 14
        targetSdkVersion 16
    }
}

应用程序/库/核心/库/ ZBarLibrary /的build.gradle

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.5.+'
    }
}
apply plugin: 'android-library'

repositories {
    mavenCentral()
}

dependencies {
    compile filetree(dir: 'libs',include: '*.jar')
}

android {
    compileSdkVersion 17
    buildToolsversion "17.0.0"

    defaultConfig {
        minSdkVersion 14
        targetSdkVersion 16
    }

    sourceSets {
        main {
            manifest.srcFile 'AndroidManifest.xml'
            java.srcDirs = ['src']
            resources.srcDirs = ['src']
            aidl.srcDirs = ['src']
            renderscript.srcDirs = ['src']
            res.srcDirs = ['res']
            assets.srcDirs = ['assets']
        }
    }
}

App目录中的命令“gradle build”生成错误：“package com …不存在”.这个包在app模块中使用,但它可以在App / libraries / Core / Core / src / main / java中找到.你可以帮帮我吗？