Image title in block.tpl.php

I followed the instructions in the following node to replace block title with HTML image.

http://drupal.org/node/44702

Now, depending on my URL, I have my title images appearing and disappering. To rephrase, when I use drupal's default URL (e.g node/10) the images disappear and when I use an alias the images reappear. What can be behind this issue? I am using BASIC as my theming template. Drupal version used is 6.15

What follows is the code in my block.tpl.php:

<?php if (!empty($block->subject)): ?>
	<?php if (substr($block->subject,0,3)=="img") {
        $tok = strtok($block->subject," ");
        while ($tok !== false)
        {
            switch (substr($tok,0,1))
            {
                case "m":
                    $type="module";
                    $name=substr($tok,2);
                    break;
                case "t":
                    $type="theme";
                    $name=substr($tok,2);
                    break;
                case "e":
                    $type="theme_engine";
                    $name=substr($tok,2);
                    break;
                case "w":
                    $imgwidth=substr($tok,2);
                    break;
                case "h":
                    $imgheight=substr($tok,2);   
                    break;
                case "i":
                    $imgfilename=substr($tok,4);
                    break;
            }
            $tok = strtok(" ");
        }
       
        echo "<div class='title block-title'><img src='".drupal_get_path($type,$name).'/'.$imgfilename."' height='".$imgheight."' width='".$imgwidth."' /></div>";
     } else { ?>
      <h3 class="title block-title"><?php print $block->subject; ?></h3>
	<?php } ?>
    <?php endif; ?>