Error on page

[Silju Augustine]

I am trying to update a record. It correctly opens the record first. but when i try to update it shows the error "Microsoft VBScript runtime (0x800A01A8)
Object required: ''
in line No 20"

this is the code that i used
Kindly help

<form method="post" action="heading.asp">

<% n1=request(trim("n1"))
n2=request(trim("n2"))
n3=request(trim("n3"))
n4=request(trim("n4"))
n5=request(trim("n5"))
n6=request(trim("n6"))
n7=request(trim("n7"))
n8=request(trim("n8"))
n9=request(trim("n9"))

DIM sd
dim rs
Set sd = Server.CreateObject("ADODB.Connection")
sd.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & _
Server.MapPath ("/logon.mdb") & ";"
sd.Open
set rs=sd.execute(update students set DOB='"&n2&"',SName='"&n9&"',Clas="&n3&",Sec='"&n4& "',"FName='"&n5&"',MName='"&n6&"',Adrs='"&n7&"',Ph one='"&n8&"' where AdmNo="&n1&")
%>
<center>
<input type="submit" value="!Successfully Saved!">