无法解析符号BR -challenge.mobile.codetribe.databind.BR

Question

apply plugin: 'com.android.application'
apply plugin: 'com.android.databinding'

android {
    compileSdkVersion 23
    buildToolsVersion "23.0.1"
    defaultConfig {
        applicationId "challenge.mobile.codetribe.databind"
        minSdkVersion 23
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }
    dataBinding {
        enabled = true
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.1.0'
    compile 'com.android.support:recyclerview-v7:23.1.0'
}