Unable to cast object

Why this code does not work

private void dataGrid_LoadingRow(object sender, Microsoft.Windows.Controls.DataGridRowEventArgs e)
    {
        //Highlighting rows

        Product product = (Product)e.Row.DataContext;

        if (product.Price > 100)
        {
            e.Row.Background = highlightBrush;
        }
        else
        {
            e.Row.Background = normalBrush;
        }
    }

}
class Product
{
    public int IdBook ;
    public string NameBook;
    public string Author;
    public string Description;
    public string DateRegister;
    public Int32 Price;
}

xaml:

            <dg:DataGrid Name="dataGrid" AutoGenerateColumns="False"  CanUserAddRows="False" CanUserDeleteRows="False"  IsReadOnly="True"                           


                    HeadersVisibility="Column" SelectedIndex="-1" Margin="0,315,0,25" Background="#FF484040" BorderBrush="#FF484040" 

SelectionChanged="dataGrid_SelectionChanged" LoadingRow="dataGrid_LoadingRow">
            <dg:DataGrid.Columns>
                <dg:DataGridTextColumn Binding="{Binding IdBook}" Header="IdBook" ></dg:DataGridTextColumn>
                <dg:DataGridTextColumn Binding="{Binding NameBook}" Header="NameBook"></dg:DataGridTextColumn>
                <dg:DataGridTextColumn Binding="{Binding Author}" Header="Author"></dg:DataGridTextColumn>
                <dg:DataGridTextColumn Binding="{Binding Price}" Header="Price"></dg:DataGridTextColumn>
                <dg:DataGridTextColumn Binding="{Binding DateRegister}" Header="DateRegister"></dg:DataGridTextColumn>
                <dg:DataGridTextColumn Binding="{Binding Description}" Header=Description" Width="*"></dg:DataGridTextColumn>
                <dg:DataGridTemplateColumn>

                    <dg:DataGridTemplateColumn.CellTemplate>
                  开发者_C百科      <DataTemplate>
                            <Button Click="Delete_Click"  ToolTip="Delete" Height="30" Width="30" FlowDirection="RightToLeft" Style="{DynamicResource GlassButton}" 

Background="{DynamicResource TileBrush}">

                            </Button>
                        </DataTemplate>
                    </dg:DataGridTemplateColumn.CellTemplate>

                </dg:DataGridTemplateColumn>
                <dg:DataGridTemplateColumn Width="15" >
                    <dg:DataGridTemplateColumn.CellTemplate>
                        <DataTemplate>
                            <CheckBox ToolTip="Select" Name="Checkbox" Height="15" Width="15" HorizontalContentAlignment="Center" HorizontalAlignment="Center" 

VerticalAlignment="Center" VerticalContentAlignment="Center">

                            </CheckBox>
                        </DataTemplate>
                    </dg:DataGridTemplateColumn.CellTemplate>
                </dg:DataGridTemplateColumn>
            </dg:DataGrid.Columns>


        </dg:DataGrid>

error :

Unable to cast object of type 'System.Data.DataRowView' to type 'BooksManagement_Version1.Product'.

It seems that the DataContext of the Row is not what you are expecting. Check that you are binding to a collection of Product. Also, if you can post the xaml for the DataGrid that would be helpful.