asp.net下载文件时出错！！
Dim Filepath As String = Label7.Text
  Dim fileStream As New FileStream(Filepath, FileMode.Open)
  Dim fileSize As Long = fileStream.Length
  Dim inta As Integer = CInt(fileSize)
  Dim OutPutFileName As String = " linkbutton1.text" 
  Response.ContentType = "application/octet-stream"
  Response.AddHeader("Content-Disposition", "attachment; filename=" & HttpUtility.UrlEncode(OutPutFileName, System.Text.Encoding.UTF8))
  Response.AddHeader("Content-Length", fileSize.ToString())
  Dim fileBuffer(inta) As Byte
  fileStream.Read(fileBuffer, 0, inta)
  fileStream.Close()
  Response.BinaryWrite(fileBuffer)
  Response.End()

linkbutton1.text为下载的文件文件名。。但是下载下来的文件却没有后缀，无法打开。。。为什么？？

------解决方案--------------------
Dim OutPutFileName As String = linkbutton1.text
不要引号