Global.asa Logout On Browser Close

I wrote global.asa file but I couldn't get what I expect.After user logs on to the system,if he/she directly closes the explorer,the time he/she logs out must be written to the database.I have logout.asp file which do this when the user click on the LOGOUT button,but if the user doesn't click it just closes the explorer what handles it??The following global.asa tries to do that but I think there is something wrong.If you examine it I would be very happy thanks...

GLOBAL.ASA

<script language=vbscript runat=server>
Sub Application_OnEnd()
session.abandon()
End Sub
Session.Timeout=1
Sub Application_OnStart()
Application("CurrentUser")=0
Application("TotalUser")=0
End Sub
Sub Session_OnEnd()
Application("CurrentUser")=Application("CurrentUser")-1
Application("TotalUser")=Application("TotalUser")-1
Set con = Server.CreateObject("ADODB.Connection")
con.Open "DSN=Address"
SQL="UPDATE tblLog SET fldTimeOut= "' & Time() & "' WHERE fldUserName= "' & Session("Admin") & "'"
con.execute(SQL)
session.abandon()
con.close
End Sub
Sub Session_OnStart()
Application("CurrentUser")=Application("CurrentUser")+1
Application("TotalUser")=Application("TotalUser")+1
End Sub
</script>