我在这个甘特图上增加了一个实际开始时间，我如何在甘特图的相应日期位置标注成绿色呢。

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点击浏览该文件:编码绘制甘特图 (1) (1).table

static dic As new Dictionary(of String, brush)
If DrawGannt Then
    Dim cr As Row  = Tables("任务").Rows(e.Row.Index)
    For Each r As DataRow In cr.Table.DataTable.Select("工程名称 = \'" & cr("工程名称") & "\'", "开始日期")
        Dim dt1 As Date = r("开始日期")
        Dim dt3 As Date = r("实际开始")
        Dim dt2 As Date = r("结束日期")
        Dim dt As Date = e.Col.Name.Replace("年","-").Replace("月_","-")
       
        If dt = dt1 Then
            e.StartDraw()
            If dic.ContainsKey(dt) = False Then
                Dim br1 As Brush = New SolidBrush(Color.FromARGB(rand.Next(255),rand.Next(255),rand.Next(255),rand.Next(255)))
                dic.add(dt, br1)
            End If
            Dim sp1 As TimeSpan = dt3-dt1
            Dim sp2 As TimeSpan = dt2-dt3
            Dim sp3 As TimeSpan = dt2-dt1
            e.Graphics.FillRectangle(dic(dt),e.x ,e.y + 5, cint(e.Width*sp1.TotalDays/sp3.TotalDays), e.Height - 10)
           
            If dt3 <> Nothing Then
                Dim br2 As Brush = New SolidBrush(Color.green)
                e.Graphics.FillRectangle(br2,e.x+cint(e.Width*sp1.TotalDays/sp3.TotalDays) ,e.y + 5, cint(e.Width*sp2.TotalDays/sp3.TotalDays), e.Height - 10)
            End If
            Dim fnt As New Font("宋体",9)
            Dim msg As String = r("任务名称")
            e.Graphics.DrawString(msg,fnt,Brushes.Red,e.x,e.y+2)
            e.EndDraw()           
        End If
    Next
End If

有两个问题麻烦帮忙看看把

1.是希望在实际开始的那一天的颜色改变成绿色，而不是这整个后面都绿了。

2.其他的甘特图显示不出来了。