These are the query parameters i use...works for me when i loop through the results
array(
'post_parent' => $post->ID,
'post_status' => 'inherit',
'post_type'=> 'attachment',
'post_mime_type' => 'image/jpeg,image/gif,image/jpg,image/png'
);
For more detail, please see official documentation for WP_Query's status parameters
