专家坐堂-做图表时遇到两个问题，请问大神们怎么处理？Foxtable(狐表) - 新一代数据库软件，完美融合Access、Foxpro、Excel、vb.net之优势，人人都能掌握的快速软件开发工具!

Dim Chart As WinForm.Chart \'定义一个图表变量

Dim Series As WinForm.ChartSeries \'定义一个图系变量

Chart = e.Form.Controls("Chart1") \' 引用窗口中的图表

Chart.VisualEffect = True \'加上这一行,让你的图表更漂亮

Chart.ChartType = ChartTypeEnum.Bar \'图表1类型该为Bar(条形)

Chart.ChartType2 = ChartTypeEnum.XYPlot \'图表2类型该为线形

Chart.DataSource = "统计表" \'设置绑定表

Chart.SeriesList.Clear() \'清除图表原来的图系

Series = Chart.SeriesList.Add() \'增加第一个图系

Series.Text = "最高分"

Series.X.DataField = "班级" \'X轴绑定到产品列

Series.Y.DataField = "总分_最高分" \'Y轴绑定到数量列

Series.TooltipText = "X = {#XVAL}, Y = {#YVAL}"

Series.LineColor = Color.Blue \'设置该图系的颜色

Series = Chart.SeriesList.Add() \'增加第二个图系

Series.Text = "最低分"

Series.X.DataField = "班级" \'X轴绑定到产品列

Series.Y.DataField = "总分_最低分" \'Y轴绑定到数量列

Chart.SeriesList2.Clear() \'清除图表原来的图系

Series = Chart.SeriesList2.Add() \'给图表2增加一个图系

Series.Text = "平均分"

Series.X.DataField = "班级" \'X轴绑定到产品列

Series.Y.DataField = "总分_平均分" \'Y轴绑定到数量列

Series.DataLabelText = "{#YVAL}"

Chart.LegendVisible = True \'显示图列

Chart.LegendCompass= CompassEnum.South \'图列显示在南方(底端)