所有支持库的版本相同

Question

我正在尝试在残酷的环境中向我的应用添加播放服务。现在我看到它给出了使用相同库级别的错误。我看不出如何解决这个问题。我在Google上搜索过，找不到任何内容。这是我的gradle模块文件：

 apply plugin: 'com.android.application'

android {
    compileSdkVersion 27
    defaultConfig {
        applicationId "bnf.xpclicker"
        minSdkVersion 24
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:27.1.1'
    implementation 'com.android.support.constraint:constraint-layout:1.1.2'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:2.1.3'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:7.4.0''
    implementation 'com.google.android.gms:play-services-games:15.0.1'
}