XP上XamlReader读取XAML失败的问题

 StringBuilder cellTemp = new StringBuilder();
            cellTemp.Append("<DataTemplate ");
            cellTemp.Append(" xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation'");
            cellTemp.Append(" xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml' ");
            cellTemp.Append(" xmlns:toolkit=\"http://schemas.microsoft.com/wpf/2008/toolkit\" ");
            cellTemp.Append("   >");
            cellTemp.Append("<Grid Width=\"{Binding RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=toolkit:DataGridCell},Path=ActualWidth}\" ");
            cellTemp.Append("     Height=\"{Binding RelativeSource={RelativeSource AncestorType=toolkit:DataGridColumnHeader},Path=ActualHeight}\"  >");
            cellTemp.Append("		<Grid.ColumnDefinitions>");
            cellTemp.Append("			<ColumnDefinition Width=\"0.16*\"></ColumnDefinition>");
            cellTemp.Append("			<ColumnDefinition Width=\"0.34*\"></ColumnDefinition>");
            cellTemp.Append("			<ColumnDefinition Width=\"0.16*\"></ColumnDefinition>");
            cellTemp.Append("			<ColumnDefinition Width=\"0.34*\"></ColumnDefinition>");
            cellTemp.Append("		</Grid.ColumnDefinitions>");
            cellTemp.Append("		<TextBlock Text=\"￥\" HorizontalAlignment=\"Right\" VerticalAlignment=\"Center\"/>");
            cellTemp.Append("		<TextBlock Grid.Column=\"1\"  Text=\"{Binding " + bindFieldSale + "}\" HorizontalAlignment=\"Left\" VerticalAlignment=\"Center\">");
            cellTemp.Append("           <TextBlock.ToolTip >");
            cellTemp.Append("               <ToolTip DataContext=\"{Binding Path=PlacementTarget,RelativeSource={x:Static RelativeSource.Self}}\">");
            cellTemp.Append("                   <WrapPanel>");
            cellTemp.Append("                       <TextBlock Text=\"￥\"/>");
            cellTemp.Append("                       <TextBlock Text=\"{Binding  Path=Text}\"/>");
            cellTemp.Append("                   </WrapPanel>");
            cellTemp.Append("               </ToolTip>");
            cellTemp.Append("         </TextBlock.ToolTip >");
            cellTemp.Append("       </TextBlock>");
            cellTemp.Append("		<TextBlock Grid.Column=\"2\"  Text=\"￥\" HorizontalAlignment=\"Right\" VerticalAlignment=\"Center\"/>");
            cellTemp.Append("		<TextBlock Grid.Column=\"3\" Text=\"{Binding "+bindFieldPercentage+"}\" HorizontalAlignment=\"Left\" VerticalAlignment=\"Center\">");
            cellTemp.Append("           <TextBlock.ToolTip>");
            cellTemp.Append("               <ToolTip DataContext=\"{Binding Path=PlacementTarget,RelativeSource={x:Static RelativeSource.Self}}\">");
            cellTemp.Append("                   <WrapPanel>");
            cellTemp.Append("                       <TextBlock Text=\"￥\"/>");
            cellTemp.Append("                       <TextBlock Text=\"{Binding  Path=Text}\"/>");
            cellTemp.Append("                   </WrapPanel>");
            cellTemp.Append("               </ToolTip>");
            cellTemp.Append("           </TextBlock.ToolTip>");
            cellTemp.Append("       </TextBlock>");
            cellTemp.Append("</Grid>");