Why does this occasionally freeze?

Basically, this makes it so a flag can be captured by either team, and the GUI above it displays how much of it has been captured so far, and when it's taken the flag turns to the color of the team. The script works perfectly, yet occasionally the bar above will completely freeze and remain black, and the flag itself cannot be reclaimed by either team, and it'll not be able to be captured for the rest of the server lifetime. Any ideas on what I did wrong?

Colors={"Dark green", "Brick yellow"}
Radius=15

function playertotal()
    local a,b=0,0
    for i, x in pairs(game.Players:GetPlayers())do
        pcall(function()
            if x.Character.Humanoid.Health>0 and (x.Character:GetModelCFrame().p-script.Parent.Parent.Base.Position).magnitude<Radius then
                if x.TeamColor==BrickColor.new(Colors[1]) then
                    a=a+1
                elseif x.TeamColor==BrickColor.new(Colors[2]) then
                    b=b+1
                end
            end
        end)
    end
    return a,b
end

function flagtick()
    if script.Parent.Capture.Value>=100 then
        script.Parent.Capture.Value=0
        if script.Parent.Owner.Value==BrickColor.new(Colors[1]) then
            script.Parent.Owner.Value=BrickColor.new(Colors[2])
        elseif script.Parent.Owner.Value==BrickColor.new(Colors[2]) then
            script.Parent.Owner.Value=BrickColor.new(Colors[1])
        else
            local a,b=playertotal()
            script.Parent.Owner.Value=BrickColor.new(a>b and Colors[1] or a<b and Colors[2])            
        end
    end

    local a,b=playertotal()
    if (a>b and script.Parent.Owner.Value~=BrickColor.new(Colors[1])) or (b>a and script.Parent.Owner.Value~=BrickColor.new(Colors[2])) then
        script.Parent.Capture.Value=script.Parent.Capture.Value+1
    end
    if ((a>b and script.Parent.Owner.Value==BrickColor.new(Colors[1])) or (b>a and script.Parent.Owner.Value==BrickColor.new(Colors[2]))) and script.Parent.Capture.Value>0 then
        script.Parent.Capture.Value=script.Parent.Capture.Value-1
    end

    script.Parent.BrickColor=script.Parent.Owner.Value
    for i, x in pairs(script.Parent.Parent.Sandbags:children()) do
        x.BrickColor=script.Parent.Owner.Value
    end

    script.Parent.BillboardGui.Frame.BackgroundColor3=Color3.new(script.Parent.Owner.Value.Color.r-.2,script.Parent.Owner.Value.Color.g-.2,script.Parent.Owner.Value.Color.b-.2)
    script.Parent.BillboardGui.Frame.Frame.BackgroundColor3=script.Parent.Owner.Value.Color

    script.Parent.BillboardGui.Frame.Frame.Frame:TweenSize(UDim2.new(script.Parent.Capture.Value/100,0,1,0),"Out","Linear",.2,true)
    script.Parent.BillboardGui.Frame.Frame.Frame.BackgroundColor3=(script.Parent.Owner.Value==BrickColor.new(Colors[1])) and BrickColor.new(Colors[1]).Color or (script.Parent.Owner.Value==BrickColor.new(Colors[2])) and BrickColor.new(Colors[2]).Color or BrickColor.new("Black").Color
end
script.Parent.BillboardGui.Adornee=script.Parent
while wait(.1) do
    flagtick()
end