Storing User Statistics

Thank you. i made some modifications on thumbs_rating_add_vote_callback function. And i dont success.

in fuct this is not about the plugin but i want to ask that question to experienced coder.

update_user_meta is not updating. if you have sparetime can you please check my code. thank you.

function thumbs_rating_add_vote_callback()
	{

		// Check the nonce - security
		check_ajax_referer( 'thumbs-rating-nonce', 'nonce' );

		global $wpdb;

		// Get the POST values

		$post_ID = intval( $_POST['postid'] );
		$type_of_vote = intval( $_POST['type'] );

        // Get the currebt User Id
        if( $post_ID == '' ) $post_ID = get_the_ID();
        $user_ID = get_current_user_id();     

		// Check the type and retrieve the meta values
        global $parameter_name;
        global $parameter_value;

		if ( $type_of_vote == 1 ){

			$meta_name = "_thumbs_rating_up";
            $parameter_name = 'positive_votes';
            //$current_user_positive_votes = get_user_meta($user_ID, $parameter_name, true);
            $current_user_positive_votes = get_user_meta($user_ID, $parameter_name, true) != '' ? get_user_meta($user_ID, $parameter_name, true) : '0';

            if($current_user_positive_votes == '')
            {
                add_user_meta($user_ID, $parameter_name, 0, false);
                //$current_user_positive_votes = get_user_meta($user_ID, $parameter_name, true);
                $current_user_positive_votes = get_user_meta($user_ID, $parameter_name, true) != '' ? get_user_meta($user_ID, $parameter_name, true) : '0';
            }

            $parameter_value = $current_user_positive_votes + 1; 

		}elseif( $type_of_vote == 2){

			$meta_name = "_thumbs_rating_down";
            $parameter_name = 'negative_votes';
            //$current_user_negative_votes = get_user_meta($user_ID, $parameter_name, true);
            $current_user_negative_votes = get_user_meta($user_ID, $parameter_name, true) != '' ? get_user_meta($user_ID, $parameter_name, true) : '0';

            if($current_user_negative_votes == '')
            {
                add_user_meta($user_ID, $parameter_name, 0, false);
                //$current_user_negative_votes = get_user_meta($user_ID, $parameter_name, true);
                $current_user_negative_votes = get_user_meta($user_ID, $parameter_name, true) != '' ? get_user_meta($user_ID, $parameter_name, true) : '0';
            }

            $parameter_value = $current_user_negative_votes + 1;

		}

		// Retrieve the meta value from the DB

		$thumbs_rating_count = get_post_meta($post_ID, $meta_name, true) != '' ? get_post_meta($post_ID, $meta_name, true) : '0';
		$thumbs_rating_count = $thumbs_rating_count + 1;

		// Update the meta value
		update_post_meta($post_ID, $meta_name, $thumbs_rating_count);
        update_user_meta( $user_id, $parameter_name, $parameter_value );

        //Update total Votes of current user
        //$total_votes = get_user_meta($user_ID, 'total_votes', true);
        $total_votes = get_user_meta($user_ID, 'total_votes', true) != '' ? get_user_meta($user_ID, 'total_votes', true) : '0';

        if($total_votes == '')
        {
            add_user_meta($user_ID, 'total_votes', 0, false);
            $total_votes = get_user_meta($user_ID, 'total_votes', true) != '' ? get_user_meta($user_ID, 'total_votes', true) : '0';
        }

        $total_votes = $total_votes + 1 ;
        //$total_votes_new_value_string = "".$total_votes_new_value;
        update_user_meta($user_id, 'total_votes', $total_votes);

        insert_user_stats($post_ID, $user_ID);

		$results = thumbs_rating_getlink($post_ID, $type_of_vote);

		die($results);
	}

	add_action( 'wp_ajax_thumbs_rating_add_vote', 'thumbs_rating_add_vote_callback' );
	add_action('wp_ajax_nopriv_thumbs_rating_add_vote', 'thumbs_rating_add_vote_callback');

endif;