jQuery plugin not loading in WordPress

jQuery plugin not loading in WordPress

I've successfully linked jQuery to WordPress within the functions.php.
However, it appears that the center.js is not loading. I say this, because
the console is giving me this error: Uncaught TypeError: Object [object
Object] has no method 'center'
I am calling all scripts with <?php wp_head(); ?> within the header.php.
Here is my functions.php:
<?php
function add_google_jquery() {
if ( !is_admin() ) {
wp_deregister_script('jquery');
wp_register_script('jquery',
("http://ajax.googleapis.com/ajax/libs/jquery/1.4.1/jquery.min.js"),
false);
wp_enqueue_script('jquery');
}
}
add_action('wp_print_scripts ', 'add_google_jquery');
// just added jQuery
function add_google_center() {
if ( !is_admin() ) {
wp_register_script('center',
("http://jquerydevbrazil.googlecode.com/svn/trunk/jquery.center.js"),
false);
wp_enqueue_script('center');
}
}
add_action('wp_print_scripts_center ', 'add_google_center');
set_post_thumbnail_size( 800, 600, 1 );
function PA_stylesheet() {
wp_enqueue_style( 'pa-style', get_stylesheet_uri() );
}
add_action( 'wp_enqueue_scripts', 'PA_stylesheet' );
function PA_javascript() {
wp_enqueue_script( 'custom-script',
get_stylesheet_directory_uri() . '/tran.js',
array( 'jquery' )
);
}
add_action( 'wp_enqueue_scripts', 'PA_javascript' );
?>
Would anyone be able to help solve this problem?