Wordpress Post Thumbnail metabox not appearing

WordPress version : 3.1 post thumbnail field not appearing in editor section except for Page editor . My Code inside function.php

add_theme_support( 'post-thumbnails', array( 'post' ) ); // Add it for posts开发者_如何学C

add_theme_support( 'post-thumbnails', array( 'slider' ) ); //For Slider Image 

add_theme_support( 'post-thumbnails', array( 'portfolio' ) ); //For Portfolio 

add_theme_support( 'post-thumbnails', array( 'book' ) ); //For Book 

    add_theme_support( 'post-thumbnails', array( 'page' ) ); // Add it for pages

As I understand it,

1. add_theme_support( 'post-thumbnails' );

2. set_post_thumbnail_size( 150, 150 );

3. add_image_size( 'portfolio', 275, 152 ); 

First function adds the support.

Second changes the size of the thumbnail, there is resize mode like above or hard crop like this,

set_post_thumbnail_size( 150, 150, true);

Which will not resize just crop.

Thirdly is a custom size set for a certain tag of posts, so for the portfolio tag the thumbnail would be 272, 152, box resize mode.

Each call to add_theme_support for 'post-thumbnails' replaces the previous settings. You need to use

add_theme_support('post-thumbnails', array('post', 'page', 'slider', 'portfolio', 'book') ); 

Personally - IMHO when you create your custom post types - adding the "post-thumbnails" to the support argument when you register the post_type.