Creating tables via module using hook_install() and drupal_install_schema()

I am new to Drupal module development. I am posting in Drupal forums first time for my first I am building a module to store links of Some social networking sites and thumbnails of those sites. I want to create couple of tables in database for which i am using drupal_install_scheme() function. But when i enable the module, no tables are generated in database.
Please help me with this.
Thanks in advance!!!

This is my code :----

// $Id$
/**
* @file
* Module for managing links of social networking sites.
*/


/**
* Implementation of hook_install().
*/
function social_site_install() {
// Use schema API to create database table.
drupal_install_schema('social_site');
}



/**
* Implementation of hook_uninstall().
*/
function social_site_uninstall() {
// Remove tables.
drupal_uninstall_schema('social_site');
}



/**
* Implementation of hook_schema().
*/
function social_site_schema() {
$schema['social_site_type'] = array(
'description' => t('Stores site types of the social_site module.'),
'fields' => array(
      'tid' => array(
        'description' => 'The primary identifier for a type.',
        'type' => 'serial',
        'unsigned' => TRUE,
        'not null' => TRUE),
      'type' => array(
        'description' => 'The machine-readable name of this type.',
        'type' => 'varchar',
        'length' => 32,
        'not null' => TRUE),
      'name' => array(
        'description' => 'The human-readable name of this type.',
        'type' => 'varchar',
        'length' => 255,
        'not null' => TRUE,
        'default' => ''),
      'description'    => array(
      'description' => 'A brief description of this type.',
      'type' => 'text',
      'not null' => TRUE,
      'size' => 'medium'),
    ),
    'primary key' => array('type'),
    ),

$schema['social_site_links'] = array(
'description' => t('Stores sites\' links according to each user.'),
 'fields' => array(
    'sid' => array(
      'description' => 'Primary identifier for site link.',
      'type' => 'serial',
      'unsigned' => TRUE,
      'not null' => TRUE),
    'uid' => array(
      'type' => 'int',
      'not null' => TRUE,
      'default' => 0,
      'description' => t('The {user}.uid of the user crating the link.')
    ),
    'timestamp' => array(
     'description' => 'A Unix timestamp indicating when this site link was created.',
     'type' => 'int',
     'not null' => TRUE,
     'default' => 0),
    'url' => array(
      'description' => 'The url of the desired site.',
      'type' => 'text',
      'not null' => TRUE,
      'size' => 'medium'),
      'tid' => array(
        'description' => 'The {social_site_type}.tid of the type which this link belongs to.',
        'type' => 'serial',
        'unsigned' => TRUE,
        'not null' => TRUE),
      'thumbnail' => array(
        'description' => 'The human-readable name of this type.',
        'type' => 'varchar',
        'length' => 255,
        'not null' => TRUE,
        'default' => ''),
    ),

    'primary key' => array('url'),
);

return $schema;
}

Thanks!!
Is there anything else I'll have to do for creating tables than this code??