realm-java: Operation not permitted in /Users/cm/Realm/realm-java/realm/realm-library/src/main/cpp/io_realm_internal_SharedRealm.cpp line 81

Operation not permitted in /Users/zaki/fromgit/realm/realm-java/realm/realm-library/src/main/cpp/io_realm_internal_SharedRealm.cpp line 92

I want create my realm file on external storage,when i use Realm.getDefaultInstance(),i get the exception.

In MyApplication.java: Realm.init(this); File directory = new File(Environment.getExternalStorageDirectory(), “RealmSamplesData”); if (!directory.exists()) directory.mkdirs(); RealmConfiguration config = new RealmConfiguration.Builder() .name(“myrealm.realm”) .directory(directory) .build(); Realm.setDefaultConfiguration(config);

In MainActivity.java: mRealm = Realm.getDefaultInstance();

#### Version of Realm and tooling
Realm version(s): 2.1.1

Android Studio version: 2.2.2

Which Android version and device: Android 4.4, on PDA device