Java – Gradle error “Cannot invoke method buildToolsVersion() on null object”

I need some help….

I’m getting this error when trying to build android .apk:

FAILURE: Build Failed with an exception. "Cannot invoke method buildToolsVersion() on null object"

I’m building on Windows via cmd.exe using commands: gradle build from gonative.io source code.

Here is my build.gradle file:

apply plugin: 'android'

android {
compileSdkVersion 21    buildToolsVersion "21.1.2"

defaultConfig {
    minSdkVersion 14
    targetSdkVersion 21
    applicationId "io.gonative.android.xeeyk"
    versionCode 13
}

signingConfigs {
    release {
        storeFile file(".. /.. /release.keystore")
        storePassword "password"
        keyAlias "release"
        keyPassword "password"
    }
}

buildTypes {
    debug {
    applicationIdSuffix ".debug"
    }
    release {
        minifyEnabled true
        proguardFiles getDefaultProguardFile('proguard-android.txt'),     'proguard-project.txt'
        zipAlignEnabled true
        signingConfig signingConfigs.release
        }
    }
}

dependencies {
compile 'com.android.support:support-v4:21.+'
compile 'com.android.support:appcompat-v7:21.0.+'
compile 'com.google.android.gms:play-services:6.1.+'
}

Can someone help me?
Thank you in advance for your help,
Ivan

CommonsWare’s answer solves the problem. Moving buildToolsVersion to the next line solved the problem. Sorry Mark, this is really a super rookie question. This should be the build.gradle file:

apply plugin: 'android'

android {
compileSdkVersion 21    
buildToolsVersion "21.1.2"

defaultConfig {
minSdkVersion 14
targetSdkVersion 21
applicationId "io.gonative.android.xeeyk"
versionCode 13
}

signingConfigs {
release {
    storeFile file(".. /.. /release.keystore")
    storePassword "password"
    keyAlias "release"
    keyPassword "password"
    }
}

buildTypes {
debug {
applicationIdSuffix ".debug"
}
release {
    minifyEnabled true
    proguardFiles getDefaultProguardFile('proguard-android.txt'),     'proguard-project.txt'
    zipAlignEnabled true
    signingConfig signingConfigs.release
        }
    }
}

dependencies {
compile 'com.android.support:support-v4:21.+'
compile 'com.android.support:appcompat-v7:21.0.+'
compile 'com.google.android.gms:play-services:6.1.+'
}