知道我该怎么做吗?这是来自捆绑器的错误消息
$ bundle install
Fetching gem metadata from http://rubygems.org/........
Fetching gem metadata from http://rubygems.org/..
Bundler could not find compatible versions for gem "dm-core":
In Gemfile:
dm-adapter-simpledb (>= 0) ruby depends on
dm-core (~> 0.10.0) ruby
dm-core (1.2.0)
这是我的 Gemfile
source 'http://rubygems.org'
gem 'sinatra'
gem 'json'
gem 'prawn'
gem 'prawn-graph'
gem 'prawn-layout'
gem 'prawn-fast-png'
gem 'prawn-qrcode'
gem 'data_mapper'
gem 'dm-core'
gem 'dm-mysql-adapter'
gem 'dm-postgres-adapter'
gem 'dm-migrations'
gem 'dm-adapter-simpledb'
gem 'aws-sdk', '~> 1.3.4'
gem 'dm-paperclip'
gem 'savon'
gem 'rmagick'
gem 'SystemTimer', :require => "system_timer", :platforms => :ruby_18
gem 'rack-timeout'
gem 'rufus-scheduler'
gem 'mail'