Login form and running code before allowing user to logo

On the login page, I'm wanting to add code to check a string in a table and compare it to a string in the current url displayed.
I'm getting a syntax error on the function called curPageURL() and don't know why. This code is in "before login" on the login page.
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strSQL = "SELECT KP from tblK"

set rs = CreateObject("ADODB.Recordset")

rs.Open strSQL, dbConnection

if not rs.eof then

session("Key")= rs("KP")

else

session("Key") = ""

end if

rs.Close : set rs = Nothing
Dim dash, underscore, plus,Ot

Dim dt, tp, webst, msg
dash = instr(Session("Key"),"-")

underscore = instr(Session("Key"),"_")

plus = instr(Session("Key"),"+")

ot = instr(Session("Key"),"#")
dt = mid(session("Key"),dash + 1,6)

tp= mid(session("Key"),underscore +1,1)

webst = mid(session("Key"),plus + 1, ot)
'**

function curPageURL()

dim s, protocol, port
if Request.ServerVariables("HTTPS") = "on" then

s = "s"

else

s = ""

end if
protocol = strleft(LCase(Request.ServerVariables("SERVER_PROTOCOL")), "/") & s
if Request.ServerVariables("SERVER_PORT") = "80" then

port = ""

else

port = ":" & Request.ServerVariables("SERVER_PORT")

end if
curPageURL = protocol & "://" & Request.ServerVariables("SERVERNAME") &

port & Request.ServerVariables("SCRIPT_NAME")

end function

'****

function strLeft(str1,str2)

strLeft = Left(str1,InStr(str1,str2)-1)

end function
'****

If Session("Key") <> "" then

If Instr(curPageURL(),webst) <> 0 then

msg = "Invalid"

beforelogin= false

Else

msg = "Validated"

beforelogin = true

End If

Else:

msg = "NA"

End If

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Then I'm also wanting to display a message on the page if login is not permitted.

Response.Write(msg)...but not sure where to put it. I'm learning where code goes a bit at a time, but still a newbie at it. Any help would be appreciated.