How can I fix this error in my map voting system?

So this is a script from SpooksHD's video of a map voting system and I have rewritten the script several times with help of the video but the error seems to not fix. The error it gives me is: ServerScriptService.Server:103: attempt to concatenate local 'mName' (a nil value) And if you want to check if I have written everything correct here is the link to spooksHD's video: [https://www.youtube.com/watch?v=1eUCfvC7F1A]. Please do try to find a solution quickly because I have nothing to do but work on my game and I can't go on without a fix for this. Here is the part of the script I think the problem is in:

local start = tick()
        while wait() do
            if tick()-start >= settings.mapVoteTime then break end
            local secondsLeft = math.floor(settings.mapVoteTime-(tick()-start))
            stats.Status.Value = secondsLeft.." "..((secondsLeft==1 and "Second")or "Seconds").." Left To Vote!"
            for a,b in pairs(Game.Special.VotingPads:GetChildren()) do
                local playersVoting, mName
                for d,c in pairs(mapVotes) do
                    if c.id == tonumber(b.Name:match("%d+")) then
                        playersVoting=#c.players
                        mName=c.mapName
                        break
                    end
                end
                b.sGui.Title.Text = mName.." - "..playersVoting.." "..((playersVoting==1 and "Voter") or  "Voters")
            end
        end

Here is the full script:

--Assets--
local rep = game.ReplicatedStorage
local assets = rep.Assets

--Maps--
local maps = assets.Maps

--Signals--
local signals = assets.Signals
local event = signals.Event
local fevent = signals.FEvent

--Static Variables--
local mapVotes = {}

--Game Variables--
local Game = workspace.Game
local stats = Game.Stats
local settings = {
    mapVoteTime=15;
    mapVoteDelay=3;
    playersRequired=1;
} 

--Primary Events--

--[[
    ARRAY = mapVotes
        MapArray
            Id
            mapName
            players
                player=userId
--]]

event.OnServerEvent:connect(function(player, variables)
    if variables.reason == "voteOnMap" then
        --First check if a player already voted on a map, if so change vote.
        for a,b in pairs(mapVotes) do
            for d,c in pairs(b.players) do
                if c.player == player.UserId then
                    table.remove(b.players, d)
                    break
                end
            end
        end
        --Add player to mapVotes
        for a,b in pairs(mapVotes) do
            if b.id == variables.ItemNum then
                table.insert(b.players, {player=player.UserId})
            end
        end
    elseif variables.reason == "removeFromVote" then
                for a,b in pairs(mapVotes) do
            for d,c in pairs(b.players) do
                if c.player == player.UserId then
                    table.remove(b.players, d)
                    break
                end
            end
        end
    end
end)

function getMap()
    local randomMap = maps:GetChildren()[math.random(1,#maps:GetChildren())]
    for a,b in pairs(mapVotes) do
        if b.mapName == randomMap.Name then
            return getMap()
        end
    end
end

while wait() do
    if #game.Players:GetPlayers() < settings.playersRequired then 
        local playersNeeded = settings.playersRequired-#game.Players:GetPlayers()
        stats.Status.Value = playersNeeded.." "..((playersNeeded==1 and "Player")or "Players").." needed to play!"
    else
        --Assign maps
        mapVotes={}
        for a,b in pairs(Game.Special.VotingPads:GetChildren()) do
            table.insert(mapVotes, {id=tonumber(b.Name:match("%d+")); mapName=getMap(); players={};})
        end

        --Fire Clients, start sending in votes.
        event:FireAllClients({reason="StartVoting"})

        --Do main loop
        local start = tick()
        while wait() do
            if tick()-start >= settings.mapVoteTime then break end
            local secondsLeft = math.floor(settings.mapVoteTime-(tick()-start))
            stats.Status.Value = secondsLeft.." "..((secondsLeft==1 and "Second")or "Seconds").." Left To Vote!"
            for a,b in pairs(Game.Special.VotingPads:GetChildren()) do
                local playersVoting, mName
                for d,c in pairs(mapVotes) do
                    if c.id == tonumber(b.Name:match("%d+")) then
                        playersVoting=#c.players
                        mName=c.mapName
                        break
                    end
                end
                b.sGui.Title.Text = mName.." - "..playersVoting.." "..((playersVoting==1 and "Voter") or  "Voters")
            end
        end

        --Get winner
        table.sort(mapVotes, function(a,b) return #a.players>#b.players end)

        for a,b in pairs(Game.Special.VotingPads:GetChildren()) do
            if tonumber(b.Name:match("%d+")) == mapVotes[1].id then
                b.sGui.Title.Text = "Winner!"
                stats.Status.Value = mapVotes[1].mapName.." was chosen!"
            else
                b.sGui.Title.Text = "Lost Vote!"
            end
        end

        wait(settings.mapVoteDelay) 
    end 
end