上传图片出了问题，帮我看看怎么回事

[dvdface]

<!--METADATA NAME="Microsoft ActiveX Data Object 2.5 Library" TYPE="TypeLib" UUID="{00000205-0000-0010-8000-00AA006D2EA4}"-->
<!-- #include file="connection.asp"-->
<%
total=Request.TotalBytes
uploadedData=Request.BinaryRead(total)
crlf=ChrB(13)&ChrB(10)
tmpData=LeftB(uploadedData,CLng(InStrB(uploadedData,crlf)))
imgStart=InStrB(uploadedData,crlf&crlf)+4
imgEnd=InStrB(imgStart+1,uploadedData,tmpData)-imgStart
imgData=MidB(uploadedData,imgStart,imgEnd)
set rs=Server.CreateObject("ADODB.Recordset")
rs.Open "img",cn,3,2,adCmdTable
rs.AddNew
if rs.RecordCount<0 then
rs("num")=1
else
rs("num")=rs.RecordCount+1
end if
rs("img").AppendChunk imgData
rs.Update
rs.Close
%>

...................................................

错误类型：
Microsoft VBScript 运行时错误 (0x800A0005)
无效的过程调用或参数: 'MidB'
/7host/up.asp, 第 10 行


浏览器类型：
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 1.0.3705)

网页：
POST 2854 ??? /7host/up.asp

POST Data:
错误 '80020009'
发生意外。

[51windows]

参考一下这个

http://www.kupage.com/webdesign/7/20031017/1651460000027pkxd20u.htm

[oydj]

检查
function MidB

[dvdface]

弄了半天发现是这里忘记减一了
tmpData=LeftB(uploadedData,CLng(InStrB(uploadedData,crlf)减一))
导致imgEnd是个负数,
所以MidB函数会出错