Pagination is not working properly in Wordpress - wordpress

Question

I am currently using wordpress in creating my websites. And i really find a problem regarding pagination. So basically to be able for you to understand what is really my problem, I will post two codes:
This is the first code:
<?php if (have_posts()) : while (have_posts()) : the_post(); ?>
<div <?php post_class() ?> id="post-<?php the_ID(); ?>">
<h2><?php the_title(); ?></h2>
<?php include (TEMPLATEPATH.'/inc/meta.php'); ?>
<div class="entry">
<?php
the_excerpt();
?>
</div>
<br/><br/>
<h3>Read More...</h3>
</div>
<?php
endwhile;
?>
<?php include (TEMPLATEPATH . '/inc/nav.php' ); ?>
<?php else : ?>
<h2>Not Found</h2>
<?php endif; ?>
In this lines of code, I used the regular loop in querying a post. Actually I did not modify the code. I also installed a plugin WP-PageNavi. There is no problem, pagination is working properly.
But when i put this line of code, about the regular loop. Pagination is not working properly. I put this line of code " " because I want only to show post in this said category.
2nd code:
Line of code
<?php query_posts('cat=8'); ?>
End line of code
<?php if (have_posts()) : while (have_posts()) : the_post(); ?>
<div <?php post_class() ?> id="post-<?php the_ID(); ?>">
<h2><?php the_title(); ?></h2>
<?php include (TEMPLATEPATH . '/inc/meta.php' ); ?>
<div class="entry">
<?php the_excerpt(); ?>
</div>
<br/><br/>
<h3>Read More...</h3>
</div>
<?php endwhile; ?>
<?php include (TEMPLATEPATH . '/inc/nav.php' ); ?>
<?php else : ?>
<h2>Not Found</h2>
<?php endif; ?>
My question is: What should I do in order for the pagination to worked properly? I really need some help with this.

Answer 1

I think the problem is the because of the two The Loop(i.e while and endwhile loop) in a page.
instead of while use foreach loop. below is the example
<?php
$args = array('category' => '8');
$postArr = get_posts($args);
if($postArr){
foreach($postArr as $details){
?>
div <?php post_class() ?> id="post-<?php echo $details->ID; ?>">
<h2><?php echo $details->post_title; ?></h2>
<?php include (TEMPLATEPATH . '/inc/meta.php' ); ?>
<div class="entry">
<?php echo $details->post_excerpt(); ?>
</div>
<br/><br/>
<h3>Read More...</h3>
</div>
<?php
}
}else{
?>
<h2>Not Found</h2>
<?php
}
?>
Note Code not tested...