Expand a LUN in storage for a pool, but the pool is not expanded

We have a problem in expanding a LUN for tank pool (zfs filesystem). The original tank pool size is 200GB, a LUN for this pool has expand to 400GB. But when we check on 'zpool status', 'df -h' are still shown the 200GB.

I already googling for it. I found many answers, for exp: set autoexpand to on, replace disk with larger than before, 'zpool online -e' .. etc. But, I am not found an answer as I wanted.

I already tried them, but still failed. I already tried with create a new slice partition inside the LUN, but it's demage all data inside and too dangerous.