complex iron.io cache error

1.9.3p392 :050 > @client = IronCache::Client.new
NOTICE: Please install 'typhoeus' gem or upgrade to Ruby 2.X for optimal performance.
 => #<IronCache::Client:0x007faa2bc3b5b8 @options_list=[:scheme, :host, :port, :user_agent, :http_gem, :project_id, :token, :api_version, :cache_name], @env=nil, @project_id="51d0807bed3d763e72003fc4", @token="fpkAVBCRPwDWAGnpr2PRJBkjgcE", @scheme="https", @host="cache-aws-us-east-1.iron.io", @port=443, @user_agent="iron_cache_ruby-1.4.0 (iron_core_ruby-0.6.2)", @api_version=1, @cache_name="default", @content_type="application/json", @rest=#<Rest::Client:0x007faa2bd98b90 @options={:gem=>nil}, @logger=#<Logger:0x007faa2d792ed8 @progname=nil, @level=1, @default_formatter=#<Logger::Formatter:0x007faa2d792a00 @datetime_format=nil>, @formatter=#<Logger::SimpleFormatter:0x007faa2d7998a0 @datetime_format=nil>, @logdev=#<Logger::LogDevice:0x007faa2d792078 @shift_size=nil, @shift_age=nil, @filename=nil, @dev=#<IO:<STDOUT>>, @mutex=#<Logger::LogDevice::LogDeviceMutex:0x007faa2d799d78 @mon_owner=nil, @mon_count=0, @mon_mutex=#<Mutex:0x007faa2d799b48>>>>, @gem=:rest_client, @wrapper=#<Rest::Wrappers::RestClientWrapper:0x007faa2ec214a8>>, @logger=#<Logger:0x007faa2ec21408 @progname=nil, @level=1, @default_formatter=#<Logger::Formatter:0x007faa2ec213b8 @datetime_format=nil>, @formatter=#<Logger::SimpleFormatter:0x007faa2ec212c8 @datetime_format=nil>, @logdev=#<Logger::LogDevice:0x007faa2ec21368 @shift_size=nil, @shift_age=nil, @filename=nil, @dev=#<IO:<STDOUT>>, @mutex=#<Logger::LogDevice::LogDeviceMutex:0x007faa2ec21340 @mon_owner=nil, @mon_count=0, @mon_mutex=#<Mutex:0x007faa2ec212f0>>>>> 
1.9.3p392 :051 > @cache = @client.cache("test_cache")
 => #<IronCache::Cache:0x007faa2d534740 @client=#<IronCache::Client:0x007faa2bc3b5b8 @options_list=[:scheme, :host, :port, :user_agent, :http_gem, :project_id, :token, :api_version, :cache_name], @env=nil, @project_id="51d0807bed3d763e72003fc4", @token="fpkAVBCRPwDWAGnpr2PRJBkjgcE", @scheme="https", @host="cache-aws-us-east-1.iron.io", @port=443, @user_agent="iron_cache_ruby-1.4.0 (iron_core_ruby-0.6.2)", @api_version=1, @cache_name="default", @content_type="application/json", @rest=#<Rest::Client:0x007faa2bd98b90 @options={:gem=>nil}, @logger=#<Logger:0x007faa2d792ed8 @progname=nil, @level=1, @default_formatter=#<Logger::Formatter:0x007faa2d792a00 @datetime_format=nil>, @formatter=#<Logger::SimpleFormatter:0x007faa2d7998a0 @datetime_format=nil>, @logdev=#<Logger::LogDevice:0x007faa2d792078 @shift_size=nil, @shift_age=nil, @filename=nil, @dev=#<IO:<STDOUT>>, @mutex=#<Logger::LogDevice::LogDeviceMutex:0x007faa2d799d78 @mon_owner=nil, @mon_count=0, @mon_mutex=#<Mutex:0x007faa2d799b48>>>>, @gem=:rest_client, @wrapper=#<Rest::Wrappers::RestClientWrapper:0x007faa2ec214a8>>, @logger=#<Logger:0x007faa2ec21408 @progname=nil, @level=1, @default_formatter=#<Logger::Formatter:0x007faa2ec213b8 @datetime_format=nil>, @formatter=#<Logger::SimpleFormatter:0x007faa2ec212c8 @datetime_format=nil>, @logdev=#<Logger::LogDevice:0x007faa2ec21368 @shift_size=nil, @shift_age=nil, @filename=nil, @dev=#<IO:<STDOUT>>, @mutex=#<Logger::LogDevice::LogDeviceMutex:0x007faa2ec21340 @mon_owner=nil, @mon_count=0, @mon_mutex=#<Mutex:0x007faa2ec212f0>>>>>, @data={"name"=>"test_cache"}> 
1.9.3p392 :052 > @cache.put("complex_item", {"greeting" => "Hello", "target" => "world"})
Rest::Wrappers::RestClientExceptionWrapper: HTTP 400 Error.
  from /Users/captainproton/.rvm/gems/ruby-1.9.3-p392@onstage2/gems/rest-2.6.3/lib/rest/wrappers/rest_client_wrapper.rb:89:in `rescue in put'
	from /Users/captainproton/.rvm/gems/ruby-1.9.3-p392@onstage2/gems/rest-2.6.3/lib/rest/wrappers/rest_client_wrapper.rb:82:in `put'
	from /Users/captainproton/.rvm/gems/ruby-1.9.3-p392@onstage2/gems/rest-2.6.3/lib/rest/client.rb:203:in `block in put'
	from /Users/captainproton/.rvm/gems/ruby-1.9.3-p392@onstage2/gems/rest-2.6.3/lib/rest/client.rb:142:in `perform_op'
	from /Users/captainproton/.rvm/gems/ruby-1.9.3-p392@onstage2/gems/rest-2.6.3/lib/rest/client.rb:202:in `put'
	from /Users/captainproton/.rvm/gems/ruby-1.9.3-p392@onstage2/gems/iron_core-0.6.2/lib/iron_core/client.rb:202:in `put'
	from /Users/captainproton/.rvm/gems/ruby-1.9.3-p392@onstage2/gems/iron_cache-1.4.0/lib/iron_cache/items.rb:44:in `put'
	from /Users/captainproton/.rvm/gems/ruby-1.9.3-p392@onstage2/gems/iron_cache-1.4.0/lib/iron_cache/caches.rb:98:in `put'
	from (irb):52
	from /Users/captainproton/.rvm/gems/ruby-1.9.3-p392@onstage2/gems/railties-3.2.13/lib/rails/commands/console.rb:47:in `start'
	from /Users/captainproton/.rvm/gems/ruby-1.9.3-p392@onstage2/gems/railties-3.2.13/lib/rails/commands/console.rb:8:in `start'
	from /Users/captainproton/.rvm/gems/ruby-1.9.3-p392@onstage2/gems/railties-3.2.13/lib/rails/commands.rb:41:in `<top (required)>'
	from script/rails:6:in `require'
	from script/rails:6:in `<main>'
1.9.3p392 :053 >