Is something missing in my theme?
Most likely. If you’re using WordPress 4.1, make sure there is no <title /> in your header.php and add the following to your functions.php:
add_theme_support( 'title-tag' );
Otherwise, make sure the title tag looks like:
<title><?php wp_title( '' ) ?></title>
You should also have <?php wp_head() ?> within your <head />, this allows WordPress & other plugins to kick out all sorts of stuff to function correctly.