android -application is not ruing on android 6

I've a problem with installing my application on android 6 . In my gradle , I've these codes :

android {
compileSdkVersion 23
buildToolsVersion "23.0.1"

defaultConfig {
    applicationId "persiandesigners.jahad.ir.book_jahad"
    minSdkVersion 8
    targetSdkVersion 23
    versionCode 1
    versionName "1.0"
}
buildTypes {
    release {
        minifyEnabled true
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}
}

I've no target in manifest .

What is the problem ? why I could not install it on android 6 ?

thanks