Hello;
missing code " ({user_name_link})" in your file "thumbnail_bit.html", from your 4images_dark template.
"thumbnail_bit.html" code should be, to display "uploaded by" function (edit your existing file, and paste this code):
[qcode]<!-- you wish detail page in a small javascript open window, use {thumbnail_openwindow} -->
<table width="100%" border="0" cellspacing="2">
<tr>
<td valign="bottom"><div align="center">
<p align="center">{thumbnail}
</div></td>
</tr>
<tr>
<td valign="bottom"><div align="center"><b>{image_name}</b> {if image_is_new}<sup class="new">{lang_new}</sup>{endif
image_is_new} ({user_name_link}) </div></td>
</tr>
<tr>
<td valign="bottom"><div align="center"><font color="#999999">{if allow_comments}{lang_comments}
{image_comments}{endif allow_comments}</font></div></td>
</tr>
<tr>
<td valign="bottom"><div align="center"><a href="{cat_url}" class="box2">{cat_name}</a></div></td>
</tr>
<tr>
<td valign="bottom"><div align="center">{lightbox_button}</div></td>
</tr>
</table>
[/qcode]
You will have also to edit "random_image.html" and "random_cat_image.html" and add at the end of the code:
[qcode]{user_name}[/qcode]