Case BETWEEN TIMESTAMP inside Where clause MySQL

Question

i would like to SUM netto FROM table raw_sugar WHERE the condition its depend on my var @now

When i query manually like this

SELECT SUM(`netto`) FROM `raw_sugar`
WHERE `time` BETWEEN '2022-2-7 5:00:00' AND '2022-2-7 13:00:00' 

the result is correctly shown, but when i use this code

SET @now    :=  '2022-2-7 8:00:00';
SET @pagi   :=  '2022-2-7 5:00:00';
SET @sore   :=  DATE_ADD(@pagi, INTERVAL + 8 hour);
SET @malam  :=  DATE_ADD(@sore, INTERVAL + 8 hour);
SET @malam2 :=  DATE_ADD(@malam, INTERVAL + 8 hour);

SELECT SUM(`netto`)
FROM `raw_sugar`
WHERE (CASE
        WHEN @now BETWEEN @pagi AND @sore THEN `time` BETWEEN @pagi AND @sore
        WHEN @now BETWEEN @sore AND @malam THEN `time` BETWEEN @sore AND @malam
        WHEN @now BETWEEN @malam AND @malam2 THEN `time` BETWEEN @malam AND @malam2
       END) 

it doesn't work, it shown NULL, is there any advice ?