You need links. Pinging Google or submitting that form just notifies them, but they aren't going to include the page unless the site has enough "rank" (for lack of a better word) to be included in their index.
Remember, they don't index the whole web, they aim to index the best X percent of the web. So you need good links to the page, as those serve as votes of what constitutes "good".
It's not a high threshold either, almost any link on a page they've already indexed will get your page indexed.