Timthumb is Not Working Please Help

i love the script and using also in my site

but the problem is some images are show and some is not

so, what was the problem ??? can you guide me Please ??

my site is http://www.thesmartconsultant.com/

IN Featured Banner and Latest Post it appear but left sidebar in tab widget it’s doesn’t appear
I use Latest TimThumb Version 2.8.11 WP 3.5.1
i also do everything like cache folder PERMISSION 777 also timthumb.php PERMISSION 777 also clean cache folder and create new folder but can’t get result
Also Check in timthumb-vulnerability-scanner But Can’t get result.

in my theme function.php file code is here

[ Moderator Note: Please post code or markup snippets between backticks or use the code button. ]

// Tabber: Get Most Popular Pos

<?php
				$thumb = get_thumbnail($post->ID, get_theme_mod('thumb_key'),get_theme_mod('thumb_key'));

				if(!$thumb)
					$thumb = get_bloginfo('template_url').'/images/default-thumb.gif';

				$url = get_bloginfo('template_url').'/timthumb.php?src='.$thumb.'&h='.$size.'&w='.$size.'&a=t&zc=1';
				echo '<a title="'.the_title_attribute( 'echo=0' ).'"><img width="'.$size.'" height="'.$size.'" src="'.$url.'" alt="'.get_the_title().'" /></a>';
			?>

// Loop File is 

<?php
				$thumb = get_thumbnail($post->ID, get_theme_mod('thumb_key'),get_theme_mod('thumb_key'));
				$width = get_theme_mod('thumb_width');
				$height = get_theme_mod('thumb_height');
				$auto = get_theme_mod('thumb_auto');

				if($thumb) {
					if($auto == 'Yes')
						$url = get_bloginfo('template_url').'/timthumb.php?src='.$thumb.'&h='.$height.'&w='.$width.'&a=t&zc=1';
					else
						$url = $thumb;

				} else {
					$url = get_bloginfo('template_url').'/images/default-thumb.gif';
				}

				echo '<a href="'.get_permalink().'" title="'.the_title_attribute( 'echo=0' ).'"><img width="'.$width.'" height="'.$height.'" src="'.$url.'" alt="'.get_the_title().'" /></a>';
			?>

Please help me to solve this issue ???

where i mistake ???

Thanks in Advance !!

Paresh Chauhan WebsiteVala