How do i make this tween in servers?

The tweening part of this script works perfectly in studio and studio server test but not in the actual game. Everything else works perfectly except the tweening. All i need help with is making the tween work in servers.

local NPC = script.Parent.UpperTorso

while true do
    local ply = game.Players:GetChildren()
    for i = 1, #ply do 
        local char = game.Workspace:findFirstChild(ply[i].Name) 
        if char ~= nil then 
            if (NPC.Position - char.UpperTorso.Position).magnitude <= 8 then 
                if ply[i]:findFirstChild("TalkingToNPC") then 
               else
                if ply[i].Gamestuff.Characters.Folder.Class.Value == "None" then
                local thing = Instance.new("StringValue",ply[i])
                thing.Name = "TalkingToNPC"
                     local ChatClone = script.ChatGui:Clone()
                     ChatClone.Name = "ChatClone"
                      ChatClone.Parent = ply[i].PlayerGui
                       ChatClone.Press:TweenPosition(UDim2.new(0.5, -150, 1, -200), "Out", "Back", 0.7, false)
                       ChatClone.KeyPress.Disabled = false
                 elseif ply[i].Gamestuff.Characters.Folder.Class.Value ~= "None" then
                local thing = Instance.new("StringValue",ply[i])
                thing.Name = "TalkingToNPC"
                    local ChatClone = script.ChatGui2:Clone()
                      ChatClone.Name = "ChatClone"
                      ChatClone.Parent = ply[i].PlayerGui
                     ChatClone.Press:TweenPosition(UDim2.new(0.5, -150, 1, -200), "Out", "Back", 0.7, false)
                     ChatClone.KeyPress.Disabled = false
                 end
                end

            elseif (NPC.Position - char.UpperTorso.Position).magnitude > 8 then 
                if ply[i].PlayerGui:findFirstChild("ChatGui") or ply[i].PlayerGui:findFirstChild("ChatGui2") or  ply[i].PlayerGui:findFirstChild("ChatClone") then --:findFirstChild("TalkingToNPC")
            ply[i]:findFirstChild("TalkingToNPC"):destroy()
            ply[i].PlayerGui.ChatClone.Press:TweenPosition(UDim2.new(0.5, -150, 1.5, -200), "In", "Back", 0.7, true)
            wait(0.8)
            ply[i].PlayerGui.ChatClone:destroy()
               end
                wait()
            end 
        end 
    end
    wait(0.1)
end