just change
dev_mount sdcard2 /mnt/sdcard 1 /devices/platform/s3c-sdhci.2/mmc_host/mmc1
dev_mount sdcard /mnt/sdcard/external_SD 1 /devices/platform/dw_mmc/mmc_host/mmc0
to
dev_mount sdcard /mnt/sdcard 1 /devices/platform/dw_mmc/mmc_host/mmc0
dev_mount sdcard2 /mnt/sdcard/external_SD 1 /devices/platform/s3c-sdhci.2/mmc_host/mmc1
*flip 1st row to 2nd row
*notice about /mnt/sdcard
*check from root explorer:
#1. "/mnt/sdcard" -> if you didn't have "/mnt/sdcard/external_SD" then create empty folder "external_SD"
#2. "/mnt/sdcard/external_SD" -> if you didn't have "/mnt/sdcard/external_SD/external_SD" then create empty folder "external_SD"
