Navigation Menu funct. broken

Hey everyone. Thanks for reading. I’m having an issue with WP Navigation Menus.

tl;dr: my navigation menus, built in the admin panel, are working in my theme on my local machine but not on my remote installation.

I recently put my WP site live here: https://www.i-am-matthew.com.

I developed the site locally. When it came time to move it remotely I did a mass export from my local WP installation and imported it (pages, posts, comments, and menus) into my newly installed 3.2.1 remote WP. I then installed the theme I was developing.

The problem is that my Navigational Menus administered through the admin panel are not functioning. The menu locations appear registered and I can assign menus to them in the admin panel, but they don’t generate on my website. wp_nav_menu seems to default to listing all of my Pages instead of using the menu specified by the theme_location argument. Not only this, but, wp_nav_menu doesn’t operate on any of the other fields given to it for styling.

Here’s what’s in my functions.php:

/****** MENUS ******/

add_theme_support( 'menus' );

function register_my_menus() {
 if ( function_exists( 'register_nav_menus' ) )
  register_nav_menus( array( 'main-nav' => 'MainNav', 'second-nav' => 'SecondNav') );
}

add_action( 'init', 'register_my_menus' );

Here’s what’s in my theme:

wp_nav_menu(
 array(
  'theme_location' => 'main-nav',
  'container' => 'div',
  'container_id' => 'menu',
  'before' => '<h1>',
  'after' => '</h1>'
));

I believe I’ve followed all of the steps covered on WP’s Navigational Menus how-to, so I’m at a little bit of a loss.

Any suggestions? Something happened between my local and my remote installs, since my menus still appear locally.

Thanks in advance!