I know that it’s not the best solution but I installed “Simple Tag” plugin which fixed the problem. Sorry for SPAM.

I found plugin’s author explain : “There is indeed a bug with tags in the current release. Until we fix this, please try adding this snippet to your theme’s functions.php file – and apologies for any inconvenience in the interim.” He advised to use the following code :

<?php

add_action( ‘parse_query’, ‘tribe_fix_tag_query’ );
function tribe_fix_tag_query( $query ) {
if ( $query->is_tag && (array) $query->get( ‘post_type’ ) != array( TribeEvents::POSTTYPE ) ) {
if ( empty( $query->query_vars[‘post_type’] ) ) {
$query->query_vars[‘post_type’] = array( ‘post’ );
}
}
}

Where I should put it ?

Hello! Thank you for your reply. Now I know that one of my plugin enforce problem. But the problem is that I really need this plugin (http://wordpress.org/plugins/the-events-calendar/). Is there anything I could do to fix it ?