利用化境无组件上传报以下错误，是怎么回事？请各位高手帮帮忙，谢谢！

用化境给的文件选取页面upfile.htm上传就不报错误，但是换成自己的页面就报以下错误，
不知道怎么回事，请各位高手帮忙！谢谢！


Microsoft VBScript 编译器错误 错误 '800a03f6'

缺少 'End'

/iisHelp/common/500-100.asp，行242

Microsoft VBScript 运行时错误 错误 '800a0005'

无效的过程调用或参数: 'MidB'

/upclass/example/upload_5xsoft.inc，行48



化境代码如下：（不知道这段代码是为了干啥，谁帮忙分析以下，全部代码在http://www.5xsoft.com/Down.aspx?id=2）
Private Sub Class_Initialize
dim RequestData,sStart,vbCrlf,sInfo,iInfoStart,iInfoEnd,tStream,iStart,theFile
dim iFileSize,sFilePath,sFileType,sFormValue,sFileName
dim iFindStart,iFindEnd
dim iFormStart,iFormEnd,sFormName
Version="化境HTTP上传程序 Version 2.0"
set objForm=Server.CreateObject("Scripting.Dictionary")
set objFile=Server.CreateObject("Scripting.Dictionary")
if Request.TotalBytes<1 then Exit Sub
set tStream = Server.CreateObject("adodb.stream")
set Data_5xsoft = Server.CreateObject("adodb.stream")
Data_5xsoft.Type = 1
Data_5xsoft.Mode =3
Data_5xsoft.Open
Data_5xsoft.Write Request.BinaryRead(Request.TotalBytes)
Data_5xsoft.Position=0
RequestData =Data_5xsoft.Read

iFormStart = 1
iFormEnd = LenB(RequestData)
vbCrlf = chrB(13) & chrB(10)
sStart = MidB(RequestData,1, InStrB(iFormStart,RequestData,vbCrlf)-1)
iStart = LenB (sStart)
iFormStart=iFormStart+iStart+1