NextGen Gallery: related pictures not showing on index.php

Hi, I use a multi-loop index. in each loop I display with the related function the gallery pictures to each post. I use the follwoing code:

<? if (nggShowRelatedImages($type, $number)) { ?>

<strong><div class="gallery-title">Gallery:&nbsp;
<span style="color: #c25b08">
<?php
$posttags = get_the_tags();
$count10=0;
if ($posttags) {
foreach($posttags as $tag) {
$count10++;
if (1 == $count10) {
echo $tag->name . ' ';
}
}
}
?>
</span>
</div></strong>

<?php } ?>

<?php related_images("tags", 10); ?>

The same code work on other pages without multi-loop. What could be the error? Any idea?