我已经使用Target SDK 26，Minimum SDK 15和Compile SDK 26做了一个应用程序，当我尝试在android 6上运行它时，Error显示'不幸停止' . 这是我的gradle文件 . 可能是什么问题呢 . 我们将非常感谢您的帮助 .

apply plugin: 'com.android.application'
android {
compileSdkVersion 26
defaultConfig {
    applicationId "com.mcash.mcashloans"
    minSdkVersion 15
    targetSdkVersion 26
    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-v7:26.0.0'
implementation 'com.android.support:design:26.1.0'
implementation 'com.android.support.constraint:constraint-layout:1.1.3'
testImplementation 'junit:junit:4.12'
androidTestImplementation 'com.android.support.test:runner:1.0.2'
androidTestImplementation 'com.android.support.test.espresso:espresso- 
core:3.0.2'
compile 'com.google.gms:google-services:3.2.1'
compile 'com.google.firebase:firebase-ads:10.0.1'

}
android-studio