world guard water-flow flag giving problems

Hello!
I am trying to stop water from flowing in a region. i put "/region flag spawn water-flow deny" and it HAS the flag as deny when i type /region info, showing water-flow: DENY

however, water still flows. any help?

EDIT: SOLVED .. I found out that there are High Frequency Flag option in the config, this needs to be set to TRUE in order for this to work.