Why can't I import the facebook SDK correctly?

I added correctly as a dependency and put the central maven repository as, there is no error in the import! But I can't access any method as the AppEventsLogger only says to create the class and NOT import. I'm following in the footsteps of Facebook Quick Starts.

build.gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 21
    buildToolsVersion "21.1.2"

    defaultConfig {
        applicationId "com.morais.daniela.doctorquiz"
        minSdkVersion 14
        targetSdkVersion 21
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}
repositories {
    mavenCentral()
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:22.0.0'
    compile 'com.android.support:support-v4:22.0.0'
    compile 'com.facebook.android:facebook-android-sdk:4.0.0'
}

log

16:59:02 Gradle build finished in 52 sec