System.NotSupportedException was unhandled
  Message="DataSet non supporta System.Nullable<>."
  Source="System.Data"
  StackTrace:
       in System.Data.DataColumn..ctor(String columnName, Type dataType, String expr, MappingType type)
       in System.Data.DataColumnCollection.Add(String columnName, Type type)
       in CrystalDecisions.CrystalReports.Engine.Table.BuildTableFromEnumerable(IEnumerable collection, Type dataClassType, String tableName)
       in CrystalDecisions.CrystalReports.Engine.Table.EnumerableToDataSet(IEnumerable collection)
       in CrystalDecisions.CrystalReports.Engine.Table.WrapAndCacheDotNetObject(Object val, Type type, IntPtr& pUnkDataSet, IntPtr& pDotNetDelegate)
       in CrystalDecisions.CrystalReports.Engine.Table.SetDataSource(Object val, Type type)
       in CrystalDecisions.CrystalReports.Engine.ReportDocument.SetDataSourceInternal(Object val, Type type)
       in CrystalDecisions.CrystalReports.Engine.ReportDocument.SetDataSource(IEnumerable enumerable)
       in testCrystal.Form1.OnLoad(EventArgs e) in C:\Documents and Settings\Administrator\Documenti\Visual Studio 2008\Projects\testCrystal\testCrystal\Form1.cs:riga 47
       in System.Windows.Forms.Form.OnCreateControl()
       in System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)
       in System.Windows.Forms.Control.CreateControl()
       in System.Windows.Forms.Control.WmShowWindow(Message& m)
       in System.Windows.Forms.Control.WndProc(Message& m)
       in System.Windows.Forms.ScrollableControl.WndProc(Message& m)
       in System.Windows.Forms.ContainerControl.WndProc(Message& m)
       in System.Windows.Forms.Form.WmShowWindow(Message& m)
       in System.Windows.Forms.Form.WndProc(Message& m)
       in System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       in System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       in System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       in System.Windows.Forms.SafeNativeMethods.ShowWindow(HandleRef hWnd, Int32 nCmdShow)
       in System.Windows.Forms.Control.SetVisibleCore(Boolean value)
       in System.Windows.Forms.Form.SetVisibleCore(Boolean value)
       in System.Windows.Forms.Control.set_Visible(Boolean value)
       in System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       in System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       in System.Windows.Forms.Application.Run(Form mainForm)
       in testCrystal.Program.Main() in C:\Documents and Settings\Administrator\Documenti\Visual Studio 2008\Projects\testCrystal\testCrystal\Program.cs:riga 18
       in System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
       in System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       in Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       in System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       in System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       in System.Threading.ThreadHelper.ThreadStart()
  InnerException: