save_post not called

Hi.

I’m trying to write my first plugin. I need to add an action to the save_post hook, but it doesn’t called.

the add action is this:
add_action( 'save_post', 'wp_thumbalizr_thumbalize_box_save' );

When I debug it with the debug bar and the List of Action Hooks is:
muplugins_loaded
registered_taxonomy
registered_post_type
load_textdomain
plugins_loaded
sanitize_comment_cookies
setup_theme
doing_it_wrong_run
wp_default_scripts
after_setup_theme
auth_cookie_valid
set_current_user
init
widgets_init
register_sidebar
wp_register_sidebar_widget
wp_default_styles
admin_bar_init
debug_bar_enqueue_scripts
dmp_panelinit_DebugMyPluginPanel
dmp_addpanel
add_admin_bar_menus
wp_loaded
auth_redirect
_admin_menu
admin_menu
admin_init
current_screen
load-post.php
admin_action_edit
parse_query
pre_get_posts
posts_selection
dbx_post_advanced
add_meta_boxes
add_meta_boxes_cctor_coupon
do_meta_boxes
admin_xml_ns
admin_enqueue_scripts
admin_print_styles-post.php
admin_print_styles
admin_print_scripts-post.php
admin_print_scripts
wp_print_scripts
admin_head-post.php
admin_head
adminmenu
in_admin_header
admin_bar_menu
wp_before_admin_bar_render
wp_after_admin_bar_render
admin_notices
all_admin_notices
post_edit_form_tag
edit_form_after_title
edit_form_after_editor
submitpost_box
post_submitbox_misc_actions
post_submitbox_start
edit_form_advanced
dbx_post_sidebar
in_admin_footer
admin_footer
loop_start
the_post
loop_end
admin_print_footer_scripts
admin_footer-post.php
shutdown

Can you help me to set the correct action.

Thanks, Ariel