信息写不进数据库！求助高手！！！

<%
connstr="Provider=Microsoft.Jet.OLEDB.4.0;Data Source="&server.mappath("gaolu/gaofa.mdb")
   set conn=server.createobject("ADODB.CONNECTION")
   conn.open connstr
bt=trim(request.form("bt"))
nr=trim(request.form("nr"))
bu=trim(request.form("bu"))
exec="insert into news (bt,nr,bu) values ('"+bt+"',"+nr+",'"+bu+"')"
conn.execute exec
conn.close
set conn=nothing
response.write "记录添加成功!"
%>