主题：未将对象引用设置到对象的实例

环境： d:as 目录下 有很多图片，图片的名字 对应  newtrj 这个表的 cn_name列（cn_name只是前缀，例如图片名为11.jpg  cn_name =11）

目的：  把as目录下 图片名能和cn_name列相同的图片 打上二维码。

用下面这段代码执行了，有的时候可以顺利执行，有的时候不可以，不知道是什么原因，请各位给指点下。 非常感谢

Dim Bar As New BarCodeBuilder
    Dim doc As New PrintDoc
    Dim rt As new prt.RenderText
 Bar.Symbology = Barpro.Symbology.QRCode
    Bar.BarRatio =0.5
    Bar.BarWidth = 1
    Bar.BarHeight = 1
    Doc.Stacking = prt.StackingRulesEnum.InlineLeftToRight

For Each r As DataRow In DataTables("newtrj").Select("id> 0")   '从数据表中提取数据
        bar.Code = r("qrcord")
              Dim fn As String = ""
                    fn = "(1):" & r("cn_name")
                    If fn <> "" And filesys.FileExists("d:\as\" & fn & ".jpg") = True Then                  
                    Dim route As String ="d:\as\" & fn & ".jpg" '原始照片存放路径
                    Dim route2 As String ="d:\qrcord\" & fn & ".jpg"
                    Dim zwidth = getImage(route).width '原始照片宽
                    Dim zheight = getImage(route).height '原始照片高
                   
                    Dim p As WinForm.Painter =e.Form.CreateControl("p", ControlTypeEnum.Painter)
                    p.Width = zwidth '原始照片宽动态赋给画板宽
                    p.Height = zheight '原始照片高动态赋给画板高
                    Dim g As Graphics = p.Graphics
                    g.Clear(Color.White)
                    g.DrawImage(getImage(route),3,3,zwidth,zheight)
                    g.DrawImage(bar.GetImage,(zwidth-10),(zheight-1800),250,250)
                    Dim rm As New prt.RenderImage '定义一个图片对象
                    rm.Image = GetImage("archives.ico") '设置图片
                    rm.Style.ImageAlign.StretchHorz = True '水平拉伸
                    g.DrawImage(rm.Image,(zwidth-50),(zheight-50),30,30) '二维码图片位置
                    Dim fnt As New Font("黑体",20,FontStyle.Bold) '黑体,10号,加粗
                    g.DrawString(fn,fnt,Brushes.Black,(zwidth-280),(zheight-200))
                    p.Repaint()
                    Dim img As Image = p.Image
                     p.Save(route2)
                    img.save(route2)
      End If                       
            Next
    MessageBox.Show("全部添加成功!", "提示")