android - Gradle DSL cannot find sources() -

i'm quite new ar , i'm using android studio 2.1.2 , tried run examples provided artoolkit.

the error says: gradle dsl method not found: 'sources()'

i'm using gradle 2.13, below code

apply plugin: 'com.android.application'  android {     compilesdkversion 23     buildtoolsversion "23.0.3"      defaultconfig.with {         applicationid "org.artoolkit.ar.samples.arsimple"         minsdkversion 15         targetsdkversion 22         versioncode 1         //integer type incremented 1 every release, major or minor, google store         versionname "1.0" //real qualified major , minor release description          //buildconfigfields.with {         //defines fields in generated java buildconfig class, in case,         // create() {           //default config, can accessed java code         //    type "int"     //e.g. "if (1 == buildconfig.value) { /*do something*/}".         //    name "value"         //see: [app or lib]/build/generated/source/buildconfig/[package path]/         //    value "1"      //     buildconfig.java         // }         //  }     }  }  android.buildtypes {     release {         minifyenabled false         proguardfiles file('proguard-rules.pro')     } }  android.productflavors { }    android.sources {     main.jni {         source {             srcdirs "src/main/nop"         }     }     main.jnilibs {         source {             srcdirs "src/main/libs"         }     } }  dependencies {     //compile 'com.android.support:support-v4:23.0.1'     //compile 'com.android.support:appcompat-v7:23.0.1' //only required when target device api level greater     compile project(':arbaselib') }                                                       //the compile , target of app being deployed device  android {     buildtoolsversion '23.0.3' } 

have followed these instructions on how set-up environment artoolkit , native development?

http://artoolkit.org/documentation/doku.php?id=4_android:android_native

please follow these instructions guide setup system if not aim develop native.

other cannot description contains less information.

the artoolkit examples ship preconfigured gradle.wrapper contains correct version , examples build out of box.

gradle.wrapper

distributionbase=gradle_user_home distributionpath=wrapper/dists zipstorebase=gradle_user_home zipstorepath=wrapper/dists distributionurl=https\://services.gradle.org/distributions/gradle-2.5-all.zip 

build.gradle (from arsimpleproj)

buildscript {   repositories {     jcenter()   }  dependencies {     classpath 'com.android.tools.build:gradle-experimental:0.2.1'      // note: not place application dependencies here; belong     // in individual module build.gradle files   } }  allprojects {   repositories {     jcenter()   } }