Custom icon for Tweets

Hi folks!
I know this may not be the right place but I’m sure that someone can lend me a hand… I spent a couple of nights awake to resolve this but I still can’t figure out how…

I use Twitter Tools and a theme from ElegantThemes (Daily Notes) to post tweets on my site under the category ‘tweet’ (ID 26).

Unfortunately (and I really can’t figure out why) it seems that the category selection that I made using that code doesn’t work so all the articles are displayed exactly in the same way.
As you can imagine by reading the code attached, I was just tryin’ to use a different icon and a slightly different layout but…surprise! No changes…
Basically I’d like to use a different icon and layout for the posts (post type = text) in a specific category (26).
Thank you so much in advance.
My website is https://www.nuovatortona.it

<div class="post" title="post_<?php echo $j; ?>">

<?php if ($arr[$j]['posttype'] == 'text') { ?>
<?php if (in_category( 26 )) { ?>
<div class="inside">
<div class="overflow">
<?php echo($arr[$j]['excerpt']); ?>
</div>
<img class="icon" src="<?php bloginfo('template_directory'); ?>/images/icon-tweet.gif" alt="twitter post" />
</div>
<?php } else { ?>
<div class="inside">
<div class="overflow">
<h2><?php echo($arr[$j]['title']); ?></h2>
<?php echo($arr[$j]['excerpt']); ?>
</div>
<img class="icon" src="<?php bloginfo('template_directory'); ?>/images/icon-post.gif" alt="article post" />
</div>
<?php }; ?>
<?php }; ?> 

<?php if ($arr[$j]['posttype'] == 'quote') { ?>
<div class="quote inside">
<div class="overflow">
<span class="quote">"</span><?php echo($arr[$j]['quote']) ?>"
</div>
<img class="icon" src="<?php echo get_template_directory_uri(); ?>/images/icon-quote.gif" alt="article post" />
</div>
<?php }; ?>

<?php if ($arr[$j]['posttype'] == 'video') { ?>
<div class="inside">
<div class="overflow">
<h2><?php echo($arr[$j]['title']); ?></h2>
<?php echo($arr[$j]['excerpt']); ?>
</div>
<img class="icon" src="<?php echo get_template_directory_uri(); ?>/images/icon-video.gif" alt="article post" />
</div>
<?php }; ?>

<?php if ($arr[$j]['posttype'] == 'audio') { ?>
<div class="inside">
<div class="overflow">
<h2><?php echo($arr[$j]['title']); ?></h2>
<?php echo($arr[$j]['excerpt']); ?>
</div>
<img class="icon" src="<?php echo get_template_directory_uri(); ?>/images/icon-audio.gif" alt="article post" />
</div>
<?php }; ?>

<?php if ($arr[$j]['posttype'] == 'photo') { ?>
<div class="inside">
<span class="photospan">
<img src="<?php echo get_template_directory_uri(); ?>/images/shadow-overlay.png" alt="thumbnail" class="thumb_overlay" />
<?php print_thumbnail($arr[$j]["thumb"], $arr[$j]["use_timthumb"], $arr[$j]['title'] , 149, 149, '', $post = $arr[$j]["post"]); ?>
</span>
<img class="icon" src="<?php echo get_template_directory_uri(); ?>/images/icon-photo.gif" alt="article post" />
</div>
<?php }; ?>

<?php if ($arr[$j]['posttype'] == 'link') { ?>
<div class="url inside">
<div class="overflow">
<?php echo($arr[$j]['link']) ?>
<br class="clear" />
<span>
<?php echo($arr[$j]['excerpt']); ?>
</span>
</div>
<img class="icon" src="<?php echo get_template_directory_uri(); ?>/images/icon-link.gif" alt="article post" />
</div>
<?php }; ?>

</div> <!-- .post -->