crashes running with `rake target=4.3`

When I execute with rake target=4.3, application crashes and puts messages below in terminal. (It's ok when I run rake target=5.1.)

$ rake target=4.3
     Build ./build/iPhoneSimulator-4.3-Development
     Build vendor/Pods
  Simulate ./build/iPhoneSimulator-4.3-Development/NanoStoreSandbox.app
dyld: lazy symbol binding failed: Symbol not found: _objc_retain
  Referenced from: /Users/satoshi/Library/Application Support/iPhone Simulator/4.3.2/Applications/A534A999-AB0C-4712-AAA6-C7214A240734/NanoStoreSandbox.app/NanoStoreSandbox
  Expected in: /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.3.sdk/usr/lib/libobjc.A.dylib

dyld: Symbol not found: _objc_retain
  Referenced from: /Users/satoshi/Library/Application Support/iPhone Simulator/4.3.2/Applications/A534A999-AB0C-4712-AAA6-C7214A240734/NanoStoreSandbox.app/NanoStoreSandbox
  Expected in: /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.3.sdk/usr/lib/libobjc.A.dylib

((null))> rake aborted!
Command failed with status (1): [DYLD_FRAMEWORK_PATH="/Applications/Xcode.a...]

Tasks: TOP => default => simulator
(See full trace by running task with --trace)

My Rakefile is here.

# -*- coding: utf-8 -*-
$:.unshift("/Library/RubyMotion/lib")
require 'motion/project'

require 'bundler/setup'
Bundler.require :default

Motion::Project::App.setup do |app|
  # Use `rake config' to see complete project settings.
  app.name = 'NanoStoreSandbox'
  app.deployment_target = '4.3'
  app.pods do
    pod 'NanoStore'
  end
end

and app/app_delegate.rb is here.

class Memo < NanoStore::Model
  attribute :body
end

class AppDelegate
  def application(application, didFinishLaunchingWithOptions:launchOptions)

    NanoStore.shared_store = NanoStore.store(:file, App.documents_path + "/nano.db")
    Memo.create(:body => 'foobarbaz')

    true
  end
end

siuying / NanoStoreInMotion

crashes running with `rake target=4.3` #11