app c++ plugin, log "Mesh::getIndex(): bad indices"

[Castle]

int wmain(int argc, wchar_t *argv[])
...
char* args[5] =
{
        "Mesh_x64d.exe",
        "-video_app", "null",
        "-data_path", "../data"
};
Unigine::EnginePtr engine(UNIGINE_VERSION, 5, args);
...
Unigine::vec3 size = { 10, 10, 10 };
Unigine::MeshPtr mesh = Unigine::Mesh::create();
mesh->addBoxSurface("box", size);
auto count = mesh->getNumIndices(0);
for (auto i = 0; i < count; ++i)
{
        auto index = mesh->getIndex(i, 0);

         // do something
}
...

why? how to correct it!