Erm, sorry, but I don't really get it.
If the article forum is FORUM_ID 35, your code should look something like this:
if FORUM_ID = "35" then
Response.Redirect "article.asp?art="& TOPIC_ID
Response.End
end if
Now you are redirecting ALL topics to article.asp, but article.asp redirects topics NOT from forum_id 35 to sitenews.asp....<