The system for voting on Minecraft servers is flawed. Users who have a slow connection have to wait for the page to load, or else the voting will bug when clicked on to vote.
The system currently works, as I see it, like this. The page loads all the information. You click on 'Vote' and it grays out the 'Vote' button, then pops up the box to enter in the details. This is the reason why sometimes people cannot vote (the page hasn't fully loaded, so when you click on the box, it simply grays it out without loading the popup).
A better way of working it is to gray it out AFTER you've voted, not before. Or maybe not graying it out and doing a check between IP and username voting (checks to see if this user has already voted and if this IP has already voted), or just username (in case there's multiple users in the same house voting, or for different reasons).
I wasn't entirely sure if this was the correct place to put this thread, but I'm hoping someone will pick this up!