Problem whit mapmanager!

[Musamba]

I don't get why I always get this error: "mapmanager: Invalid map specified"

function getRandomMapCompatibleWithGamemode(gamemode) 
    local compatibleMaps = exports.mapmanager:getMapsCompatibleWithGamemode(gamemode) 
     
    if #compatibleMaps == 0 then 
        outputDebugString("CLIMBING: No maps.") 
        return false 
    end 
    local map = compatibleMaps[math.random(1, #compatibleMaps)] 
    if exports["mapmanager"].isMap(map) then 
        return map 
    else 
        outputDebugString("CLIMBING: Map not compatible("..getResourceName(map)..")") 
        return false 
    end 
end 
  
function lastCheckpoint(player) 
    outputChatBox(getPlayerName(player).. " #ffffffhas won the match!", root, 0, 0, 0, true) 
    if not exports["mapmanager"].changeGamemodeMap(getRandomMapCompatibleWithGamemode(getThisResource()), getThisResource()) then 
        outputDebugString("CLIMBING: Map not changed.") 
    end 
end 
addEvent("lastCheckpoint", true) 
addEventHandler("lastCheckpoint", root, lastCheckpoint)