My gui isn't working? [THE MAD BLOXXER]

I have a regular script and a local script.

The local script is inside the gui. The regular script is the control.

My script shows what class they are(Sheriff, Bloxxer, Bystander). Whenever my script gets to that part, it doesn't show what they are.

Also, my local script doesn't show the intermission. Help?

ERROR: 14:19:08.441 - ReplicatedStorage.RemoteEvent: OnClientEvent can only be used on the client

INTERMISSION

function secondstotimer(seconds)
    local minutes = math.floor(seconds / 60)
    local remainingseconds = seconds % 60
    if remainingseconds <= 0 then
        remainingseconds = "00"
    elseif remainingseconds <= 9 then
        remainingseconds = "0" .. remainingseconds
    end
    return tostring(minutes) .. ":" .. remainingseconds
end

CLASSES

event.OnClientEvent:connect(function(...)
    local tuple = {...}
    if tuple[1] == "Result" then
        if tuple[2] == "BloxxerWin" then
            resultname.Text = "Mad Bloxxer wins!"
            resultname.TextColor3 = Color3.new(1, 74/255, 77/255)
            resultdesc.Text = "All players were bloxxed."
        else
            resultname.Text = "Players win!"
            resultname.TextColor3 = Color3.new(111/255, 149/255, 1)
            resultdesc.Text = "All players were bloxxed."
        end
        resultprompt.Visible = true
        resultprompt.Position = UDim2.new(0, -400, .5, -92)
        resultprompt:TweenPosition(UDim2.new(.5, -170, .5, -92), "Out", "Quad", 1)
        wait(7)
        resultprompt:TweenPosition(UDim2.new(1, 60, .5, -92), "Out", "Quad", 1)
    elseif tuple[1] == "Class" then
        if tuple[2] == "Bloxxer" then
            classname.Text = "You are the Mad Bloxxer"
            classname.TextColor3 = Color3.new(1, 74/255, 77/255)
            classdesc.Text = "Your goal is to blox everyone!"
        end
        elseif tuple[2] == "Sheriff" then
            classname.Text = "You are the Sheriff"
            classname.TextColor3 = Color3.new(111/255, 149/255, 1)
            classdesc.Text = "Your goal is to find the Mad Bloxxer and put them away for good!"
        else
            classname.Text = "You are a Bystander"
            classname.TextColor3 = Color3.new(117/255, 1, 156/255)
            classdesc.Text = "Your goal is to help the Sheriff find the Mad Bloxxer."
        end
        classprompt.Visible = true
        classprompt.Position = UDim2.new(0, -400, .5, -92)
        classprompt:TweenPosition(UDim2.new(.5, -170, .5, -192), "Out", "Quad", 1)
        wait(7)
        classprompt:TweenPosition(UDim2.new(1, 60, .5, -92), "Out", "Quad", 1)
    end)

FIRES CLASSES

if player == bloxxer then
	local sword = serverstorage:WaitForChild("Sword"):clone()
	sword.Parent = backpack
	event:FireAllClients("Class", "Bloxxer")
elseif player == sheriff then
	local gun = serverstorage:WaitForChild("Gun"):clone()
	gun.Parent = backpack
	event:FireAllClients("Class", "Sheriff")
else
	event:FireAllClients("Class", "Bystander")
	end
end

RESULTS

local gameresult = "PlayersWin"
if bloxxeractive then
	if #contestants >= 2 then
		event:FireAllClients("Result", "PlayersWin")
	else
		gameresult = "BloxxerWin"
		event:FireAllClients("Result", "BloxxerWin")
	end
else
	event:FireAllClients("Result", "BloxxerWin")
end