Did you edit the Votingselection?
Goto
Default -> Voting GameConfig -> select your Gametype -> click edit -> to add Mutators select them with holding down the CTRL-Key
If you dont do this, each IngameMapvote will load "nothing"
All your infos are correct and a normal server reation
Teh conflict, doesnt matter, its a normal reaction if you switch the map via webadmin