问从datagridview复制带有标题的单元格

EN

if (dataGridView1.GetCellCount(DataGridViewElementStates.Selected) > 0)
{
    foreach (DataGridViewColumn c in dataGridView1.Columns)
    {
        c.SortMode = DataGridViewColumnSortMode.NotSortable;
    }

    dataGridView1.SelectionMode = DataGridviewSelectionMode.ColumnHeaderSelect;                 //only the column headers will be copied
    dataGridView1.ClipboardCopyMode = DataGridViewClipboardCopyMode.EnableWithAutoHeaderText;   //.EnableWithAutoHeaderText;
                                                                                                                                // Add the selection to the clipboard.
    Clipboard.SetDataObject(dataGridView1.GetClipboardContent());  //Here it goes wrong
}

System.ArgumentNullException: 'Value cannot be null.
Parameter name: data'

System.ArgumentNullException occurred
  HResult=0x80004003
  Message=Value cannot be null.
Parameter name: data
  Source=System.Windows.Forms



StackTrace:
   at System.Windows.Forms.Clipboard.SetDataObject(Object data, Boolean copy, Int32 retryTimes, Int32 retryDelay)
   at System.Windows.Forms.Clipboard.SetDataObject(Object data)
   at Q_ProtoType.FormMain.MenuItemNew_Click(Object sender, EventArgs e) in c:\Data\Programma\Development\VSSource - oefen_new_functions\Q_ProtoType\Q_ProtoType\FormMain.cs:line 895
   at System.Windows.Forms.MenuItem.OnClick(EventArgs e)
   at System.Windows.Forms.MenuItem.MenuItemData.Execute()
   at System.Windows.Forms.Command.Invoke()
   at System.Windows.Forms.Command.DispatchID(Int32 id)
   at System.Windows.Forms.Control.WmCommand(Message& m)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.DataGridView.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
   at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
   at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Application.Run(Form mainForm)
   at Q_ProtoType.Program.Main() in c:\Data\Programma\Development\VSSource - oefen_new_functions\Q_ProtoType\Qx_ProtoType\Program.cs:line 42