主题：请教，如何解决导出时出现错误提示

Dim dlg As New SaveFileDialog '定一个新的SaveFileDialog
dlg.Filter= "Excel文件|*.xls" '设置筛选器
Dim ss As String
If dlg.ShowDialog = DialogResult.Ok Then '如果用户单击了确定按钮
    ss = dlg.FileName
   If FileSys.FileExists("& ss &") = True Then
      FileSys.DeleteFile("& ss &",2,2) '则彻底删
   End If
   Dim cn As String
   For Each cl As Col In Tables("S运输合同查询_Table1").Cols
       Dim p As String = cl.Name
       If  Tables("S运输合同查询_Table1").Cols(p).Visible Then
           cn = cn & p & ","
       End If     
   Next
    cn = cn.TrimEnd(",","")
    Dim ex As New Exporter
    ex.SourceTableName = "S运输合同查询_Table1" '指定导出表
    ex.FilePath = ss  '指定目标文件
    ex.Format = "Excel" '导出格式为Excel
    ex.Fields = cn '指定导出字段
    ex.Export() '开始导出
End If