为什么用磁盘序列号加密过的代码不能被复制安装？

default.asp
＜html＞
＜head＞
＜title＞星河影动之磁盘序列号加密代码存取管理＜/title＞
＜/head＞
＜% dim conn,fs,f
set conn = server.createobject("adodb.connection")
conn.open "driver={microsoft access driver (*.mdb)};uid=;pwd=3302;dbq="&server.mappath("id.mdb")
set fs=server.createobject("scripting.filesystemobject")
testdrive=server.mappath("/driveinfo.asp")
' 通过mappath获得当前盘盘符.
testdrive=left(testdrive,3)
set f=fs.getdrive(testdrive)
' 调用getdrive方法赋予驱动器一个变量.
mysql="select * from driveinfo where id=1"
set rscheck = server.createobject("adodb.recordset")
rscheck.open mysql,conn,1,1
fser=trim(f.serialnumber)
' 获得当前盘序列号.
strserno=trim(rscheck.fields("serno"))
strmark=rscheck.fields("wrimark")

' wrimark值为0表示代表合法用户未安装系统,值为1代表该系统已安装.值为1且序列号与当前盘不符时,则判定为非法复制用户
if strserno＜＞fser and strmark=0 then
' 如是第一次安装,则设置写盘标志为1.
session("pass")=true
' 定义用户session,并设置为全局asp文档标识变量.
set rsmain = server.createobject("adodb.recordset")
mysql1="update driveinfo set serno="&fser&", wrimark=1"
rsmain.open mysql1,conn,1,2
response.write("＜a href='success.asp'＞安装成功!欢迎光临随风起舞存取站点!＜/a＞"＝
set rsmain=nothing
else
if strserno=fser then
' 合法用户可再次进入.
session("pass")=true
response.write("＜a href='success.asp'＞再次欢迎!您已被随风起舞授权,允许进行存取...＜/a＞"＝
else
' 非法复制用户.
session("pass")=false
response.write("＜a href='fail.htm'＞it is illegal to copy the website's asp document. you are not rigrt to  use the program.＜/a＞"＝
end if
end if
set f=nothing
set fs=nothing
%＞
＜/html＞