TFS 2010: почему невозможно Dictionary с XamlWriter.Save, когда я могу использовать XamlReader для десериализации

public static string GetXml(Dictionary<string, object> parameters)
{
    return XamlWriter.Save(parameters);
}

Вышеуказанный оператор возвращает NotSupportedException.

Странно то, что я могу использовать XamlReader для сериализации словаря.

public static Dictionary<string, object> GetParameters(IBuildDetail buildDetail, string buildDefinition)
{
    var tfsProject = buildDetail.BuildDefinition.TeamProject;
    var buildServer = buildDetail.BuildServer;
    var buildDef = buildServer.GetBuildDefinition(tfsProject, buildDefinition);
    using (var stringReader = new StringReader(buildDef.ProcessParameters))
    {
        using (var xmlTextReader = new XmlTextReader(stringReader))
        {
            return (Dictionary<string, object>) XamlReader.Load(xmlTextReader);
        }
    }
}

XML:

<?xml version="1.0" ?>
<Dictionary x:TypeArguments="x:String, x:Object" xmlns="clr-namespace:System.Collections.Generic;assembly=mscorlib" xmlns:mtbwa="clr-namespace:Microsoft.TeamFoundation.Build.Workflow.Activities;assembly=Microsoft.TeamFoundation.Build.Workflow" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

  <mtbwa:BuildSettings ProjectsToBuild="$/XXX/Product/Company.XXX.Common/Company.XXX.Common.Basic/Company.XXX.Common.Basic.csproj" x:Key="BuildSettings">

    <mtbwa:BuildSettings.PlatformConfigurations>

      <mtbwa:PlatformConfigurationList Capacity="4">

        <mtbwa:PlatformConfiguration Configuration="DEMO" Platform="AnyCPU"/>

        <mtbwa:PlatformConfiguration Configuration="Release" Platform="AnyCPU"/>

      </mtbwa:PlatformConfigurationList>

    </mtbwa:BuildSettings.PlatformConfigurations>

  </mtbwa:BuildSettings>

  <mtbwa:TestSpecList Capacity="0" x:Key="TestSpecs"/>

  <x:String x:Key="BuildNumberFormat">
    $(BuildDefinitionName) 6.0.0$(Rev:.r)
  </x:String>

  <mtbwa:CodeAnalysisOption x:Key="RunCodeAnalysis">
    Never
  </mtbwa:CodeAnalysisOption>

  <mtbwa:AgentSettings MaxWaitTime="00:15:00" TagComparison="MatchExactly" Tags="" x:Key="AgentSettings"/>

  <x:Boolean x:Key="AssociateChangesetsAndWorkItems">
    False
  </x:Boolean>

  <x:Boolean x:Key="CreateWorkItem">
    False
  </x:Boolean>

  <x:Boolean x:Key="PerformTestImpactAnalysis">
    False
  </x:Boolean>

  <x:Boolean x:Key="CreateLabel">
    False
  </x:Boolean>

  <x:Boolean x:Key="DisableTests">
    True
  </x:Boolean>

  <x:Boolean x:Key="DoCheckinAssemblyInfoFiles">
    True
  </x:Boolean>

  <x:String x:Key="AssemblyVersionPattern">
    6.0.0.0
  </x:String>

  <x:String x:Key="AssemblyFileVersionPattern">
    6.0.0.B
  </x:String>

  <x:Boolean x:Key="UseObfuscation">
    True
  </x:Boolean>

  <x:String x:Key="ObfuscatorFilePath">
    C:\Program Files (x86)\LogicNP Software\Crypto Obfuscator For .Net 2011 R3\co.exe
  </x:String>

  <x:String x:Key="ObfuscatorProjectFile">
    $/XXX/Product/BuildProcess/Company.XXX.ZZZ.obproj
  </x:String>

  <x:String x:Key="ProjectPath">
    $/XXX/Product/Company.XXX.Common
  </x:String>

</Dictionary>