我在获取 Microsoft Charting 时遇到问题：
System.Web.DataVisualization.dll
在 IIS 7 上的 Windows Server 2008 上以中等信任模式工作
使用 .Net 3.5
在 Rackspace 的云站点上的环境中。
我从 Rackspace 托管环境收到此错误消息：
Security Exception
Description: The application attempted to perform an operation not allowed by the security policy. To grant this application the required permission please contact your system administrator or change the application's trust level in the configuration file.
Exception Details: System.Security.SecurityException: That assembly does not allow partially trusted callers.
我已经在我们的本地暂存环境中设置了一个站点来测试中等信任度，我收到以下消息：
Required permissions cannot be acquired.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.Security.Policy.PolicyException: Required permissions cannot be acquired.
Source Error:
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
Stack Trace:
[PolicyException: Required permissions cannot be acquired.]
System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Boolean checkExecutionPermission) +10239406
System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Int32& securitySpecialFlags, Boolean checkExecutionPermission) +97
[FileLoadException: Could not load file or assembly 'System.Web.DataVisualization, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)]
System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection) +0
System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +416
System.Reflection.Assembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +166
System.Reflection.Assembly.Load(String assemblyString) +35
System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +190
[ConfigurationErrorsException: Could not load file or assembly 'System.Web.DataVisualization, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)]
System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective) +11204104
System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory() +388
System.Web.Configuration.CompilationSection.LoadAssembly(AssemblyInfo ai) +232
System.Web.Configuration.AssemblyInfo.get_AssemblyInternal() +48
System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig) +210
System.Web.Compilation.BuildProvidersCompiler..ctor(VirtualPath configPath, Boolean supportLocalization, String outputAssemblyName) +76
System.Web.Compilation.ApplicationBuildProvider.GetGlobalAsaxBuildResult(Boolean isPrecompiledApp) +283
System.Web.Compilation.BuildManager.CompileGlobalAsax() +50
System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +676
[HttpException (0x80004005): Could not load file or assembly 'System.Web.DataVisualization, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)]
System.Web.Compilation.BuildManager.ReportTopLevelCompilationException() +76
System.Web.Compilation.BuildManager.EnsureTopLevelFilesCompiled() +1012
System.Web.Hosting.HostingEnvironment.Initialize(ApplicationManager appManager, IApplicationHost appHost, IConfigMapPathFactory configMapPathFactory, HostingEnvironmentParameters hostingParameters) +1025
[HttpException (0x80004005): Could not load file or assembly 'System.Web.DataVisualization, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. Failed to grant minimum permission requests. (Exception from HRESULT: 0x80131417)]
System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +11297830
System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +88
System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +4336948
Version Information: Microsoft .NET Framework Version:2.0.50727.4200; ASP.NET Version:2.0.50727.4016
Rackspace不会在 Rackspace 云站点服务器上安装 MSChart.exe 包。