LeakCanary - D/LeakCanary: Could not attempt cleanup, leak storage not writable

Question

I added LeakCanary in My Application. Here is my Application Class

public class GlobalClass extends Application{

    private RefWatcher refWatcher;
    @Override public void onCreate() {
        super.onCreate();
        Log.w("Trendy", "LeakCanary Installation");
        refWatcher = LeakCanary.install(this);
    }

    public static RefWatcher getRefWatcher(Context context) {
        GlobalClass application = (GlobalClass) context.getApplicationContext();
        return application.refWatcher;
    }
}

But at startup it says

D/LeakCanary: Could not attempt cleanup, leak storage not writable.

I have already give External Read/Write rights to my application

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

Please help me to understand what I am doing wrong here.