Hmm it works for me, any chance you've gotten a hold of the Admin or GM?
Instead of Forums it's best to try and get on their Discord
Or perhaps create a ticket in game at the GM Assistant NPC in Prontera
And are you logged onto the main account trying to vote?
Because yes, every 12 hours or so you should be able to vote again.
I haven't done recently but I can see if it works for me.