重叠的最后两行动态创建的网格在wpf c#

我动态地创建了一个有两列的Grid控件，并使用第一列中的数据库数据和第二列中的文本框控件填充它的行。但是最后两行网格是重叠的。下面是我的代码片段。

    if (comboBox1.SelectedIndex > 0)
    {
        // Create the Grid
        Grid DynamicGrid = new Grid();
        DynamicGrid.Width = 400;
        DynamicGrid.HorizontalAlignment = HorizontalAlignment.Left;
        DynamicGrid.VerticalAlignment = VerticalAlignment.Top;
        DynamicGrid.ShowGridLines = true;
        DynamicGrid.Background = new SolidColorBrush(Colors.LightSteelBlue);
        //Adding columns to datagrid
        ColumnDefinition gridCol1 = new ColumnDefinition();
        ColumnDefinition gridCol2 = new ColumnDefinition();
        DynamicGrid.ColumnDefinitions.Add(gridCol1);
        DynamicGrid.ColumnDefinitions.Add(gridCol2);
        // Add first column header
        TextBlock txtBlock1 = new TextBlock();
        txtBlock1.Text = "Particulars";
        txtBlock1.FontSize = 14;
        txtBlock1.FontWeight = FontWeights.Bold;
        txtBlock1.Foreground = new SolidColorBrush(Colors.Green);
        txtBlock1.VerticalAlignment = VerticalAlignment.Top;
        Grid.SetRow(txtBlock1, 0);
        Grid.SetColumn(txtBlock1, 0);
        // Add second column header
        TextBlock txtBlock2 = new TextBlock();
        txtBlock2.Text = "Amount";
        txtBlock2.FontSize = 14;
        txtBlock2.FontWeight = FontWeights.Bold;
        txtBlock2.Foreground = new SolidColorBrush(Colors.Green);
        txtBlock2.VerticalAlignment = VerticalAlignment.Top;
        Grid.SetRow(txtBlock2, 0);
        Grid.SetColumn(txtBlock2, 1);
        //// Add column headers to the Grid
        DynamicGrid.Children.Add(txtBlock1);
        DynamicGrid.Children.Add(txtBlock2);
        RowDefinition gridRow;
        TextBlock par;
        TextBox amt;
        int i = 1;
        string pjt = comboBox1.SelectedItem.ToString();
        //Display all the Particulars
        SqlCeConnection con;
        con = dbConnection();
        SqlCeCommand cmd;
        string sql = "select * from " + pjt;
        try
        {
            cmd = new SqlCeCommand(sql, con);
            SqlCeDataReader rdr = cmd.ExecuteReader();
            int ordName = rdr.GetOrdinal("Name");
            while (rdr.Read())
            {
                string nam = rdr.GetString(ordName);
                gridRow = new RowDefinition();
                gridRow.Height = new GridLength(45);
                DynamicGrid.RowDefinitions.Add(gridRow);
                par = new TextBlock();
                par.Text = nam;
                par.FontSize = 12;
                par.FontWeight = FontWeights.Bold;
                Grid.SetRow(par, i);
                Grid.SetColumn(par, 0);
                amt = new TextBox();
                amt.Height = 20;
                amt.Width = 190;
                amt.Foreground = new SolidColorBrush(Colors.Black);
                Grid.SetRow(amt, i);
                Grid.SetColumn(amt, 1);
                DynamicGrid.Children.Add(par);
                DynamicGrid.Children.Add(amt);
                i++;
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show("Error: " + ex);
        }
        this.Content = DynamicGrid;
    }

我不明白为什么会出现这种重叠。