Backendless.init() crach

Hi. My App is crach and force close when i insert below code in onCreate() method in Activity:

Backendless.init(this , APP_ID ,SECRET_KEY,"v1");

please guide me.
my dependencies like as below:

dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.1.1'
    compile 'com.backendless:android:3.0.6'
}