wp_query and pagination

Hi to all. I know my topic is already discussed in forum, but none of solutions i’ve read worked for me. I’ve spent many hours to search but i cannot resolve. I have a loop with wp_query and i cannot paginate it.

global $wp_query;
	$cat_id = get_query_var('cat');
	$category_name=get_the_category_by_ID($cat_id);
	$category_link = get_category_link($cat_id);

Then i call the wp_query

$paged=get_query_var('paged');
$my_query = new WP_Query('cat='.$cat_id.'&posts_per_page=60&paged=$paged');

Then the loop and lastly i call the pagination functions:

next_posts_link('Next posts', $my_query->max_num_pages);
previous_posts_link('Previous posts', $my_query->max_num_pages);

Then reset the data for other queries

wp_reset_postdata();

This code seems right for me: but don’t work. On my server(localhost:8888) i have a 404 page (page not found) when i click on pagination links. On the domain of the site instead of 404 page it show always the same posts by clicking on pagination links.

I cannot understand the problem. Please someone help me i’m getting crazy with this.

Thank to all and excuse me for my bad english