Menu Not showing in my Theme Dashboard

I m trying 2 develop a theme using wp version 3.5.2. I have made a template with bootstrap and now trying to convert it as theme. but problem is that I cant register the dropdown menu to my theme. I add the following code in theme function.php file:
function custom_navigation_menus() {

$locations = array(
'primary' => __( 'Primary Navigation', 'WP_Bstrap' ),

);
register_nav_menus( $locations );

}

// Hook into the 'init' action
add_action( 'init', 'Primary Navigation' );

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as fur I know after adding this code the menu should show in Dashboard>apperiance>. but there is nothing. Plz help me…It is very appreciable if anyone suggest any good tutorial on word+bootstrap dropdown menu