LIMIT not working on complex query

I made a function that generates a complex query that calculates points for my search engine. It gets the results right, but I cannot limit the output rows... Here's the query generated for a 2-words search ("lorem ipsum"):

SELECT SQL_CALC_FOUND_ROWS
    `Search`.`model` AS `model`, 
    `Search`.`foreign_key` AS `id`, 
    SUM(`Search`.`points`) AS `points`
FROM (
    SELECT
        `i18n`.`foreign_key`, `i18n`.`model`,
        (CASE 
            WHEN `i18n`.`field` = "name" THEN 50
            WHEN `i18n`.`field` = "s_desc" THEN 20
        END) AS `points`
    FROM
        `i18n`
    WHERE
        `i18n`.`field` IN ("name", "s_desc") AND
        `i18n`.`locale` = "en-us" AND
        (`i18n`.`content` LIKE "lorem%" OR `i18n`.`content` LIKE "% lorem%")

    UNION ALL

    SELECT
        `tagged`.`foreign_key`, `tagged`.`model`, 
        "50" as `points`
    FROM
        `tagged`
    INNER JOIN
        `tags` ON
            `tags`.`id` = `tagged`.`tag_id` AND
            `tags`.`name` = "lorem"
    WHERE
        `tagged`.`language` = "en-us"
     UNION ALL 
    SELECT
        `i18n`.`foreign_key`, `i18n`.`model`,
        (CASE 
            WHEN `i18n`.`field` = "name" THEN 50
            WHEN `i18n`.`field` = "s_desc" THEN 20
        END) AS `points`
    FROM
        `i18n`
    WHERE
        `i18n`.`field` IN ("name", "s_desc") AND
        `i18n`.`locale` = "en-us" AND
        (`i18n`.`content` LIKE "ipsum%" OR `i18n`.`content` LIKE "% ipsum%")

    UNION ALL

    SELECT
        `tagged`.`foreign_key`, `tagged`.`model`, 
        "50" as `points`
    FROM
        `tagged`
    INNER JOIN
        `tags` ON
            `tags`.`id` = `tagged`.`tag_id` AND
            `tags`.`name` = "ipsum"
    WHERE
        `tagged`.`language` = "en-us"
    ) `Search`
GROUP BY
    `Search`.`model`,
    `Search`.`foreign_key`
ORDER BY
    `points` DESC;
LIMIT 5 OFFSET 0

Note that I also tried LIMIT 5, 0 and only LIMIT 5. It returns all hits, not only the first 5. What am I doing wrong?