moving *.tpl into "templates" folder, but Drupal does not recognize them. How? I am building a custom theme. Currently, I put all the overridden *.tpl files under the theme root folder; it would be more clean and meaningful to put those files under "mytheme/templates", but Drupal does not recognize them after I move them. (I did clear the cache.)

Did I miss any steps?
I've also run into a situation where I had to create a page.tpl.php file before Drupal would recognize other page--foo.tpl.php files.