Persits.Upload.1 错误 '800a0009' Index out of range. 请教各位这个错误问题

Persits.Upload.1 错误 '800a0009'
Index out of range.

出现问题的原因是:我如果上传有图片的话,那能成功的，但是如果我不上传图片的,就会出现上面的错误!
还有就是如何判断是他是否有上传图片!

[bold]我的代码如下:[/bold]    
         Set Upload = Server.CreateObject("Persits.Upload")
    Upload.OverwriteFiles = True    
    Upload.SetMaxSize 101000, True
    Upload.Save

         Set Image_file=Upload.Files(1)
        Select Case Image_file.Ext
            Case ".jpg"
                FileExt=".jpg"
            Case ".gif"
                FileExt=".gif"
            Case ".jpeg"
                FileExt=".jpeg"
            Case ".bmp"
                FileExt=".bmp"
            Case Else
            Response.write "请上传.gif，.bmp，.jpg图片！"
            Response.End
        End Select
        
        IF Trim(FileExt)="" Then
            Response.Write "<script>alert('请上传.gif，.bmp，.jpg图片！');history.go(-1);</script>"
            Response.End()
        End IF
        Image_file.SaveAs FilePath&FileName&FileExt'保存地址有文件名
        DoctorPhoto="/UploadFiles/"&sj&"/"&FileName&FileExt'图片路径