No Value Given For One Or More Required Parameters Code Plz Correct It?

I want to insert a value into the database.The values are obtained from textboxes.When i try to insert i am ending up with the error:

No value given for one or more required parameters

The part of the code is:

new1 = Request.Form("new")
tab = request.form("stcode")

<%sql="INSERT INTO movable1 (" & TAB & ") VALUES(" & new1 & ")"
conn.execute(sql)
if err<>0 then
response.write("Error")
else
response.write("The " & new1 & " was added under " & tab & ".")
end if
%>

the field is a numeric field.Could anyone figure out what is the fault?