How do you make a model's transparency change when dragging it?

So far, I have this script. It clones a Model called 'Mini1' from the ReplicatedStorage. It does place down the model but the only problem it has is the Transparency when placing down. Not a single brick from the model becomes see through. In fact, it's invisible. I can't be able to fix this after several tries. Can someone help?

Here is the code:

a = script.Parent

function checkPressed(btn)
    a.MouseButton1Down:wait() 
    mouse = game.Players.LocalPlayer:GetMouse()
    clone = game.ReplicatedStorage.Mini1:Clone()
    wait()
    clone:GetChildren().Transparency = 0.5
    mouse.TargetFilter = clone
    dragging = true
    wait()
    while dragging do --set position until...
        wait()
        clone:MoveTo(Vector3.new(mouse.Hit.p.X, mouse.Hit.p.Y + (clone:GetExtentsSize().Y / 2), mouse.Hit.p.Z))
        wait()
        mouse.Button1Down:connect(--mouse down
        function() 
            dragging = false
            clone.Parent = workspace
            clone:GetChildren().Transparency = 0
            drg = true
            while drg do
                wait()
                mouse.Button1Up:connect(function()
                    mouse.TargetFilter = nil
                    drg = false
                end
                )
            end
        end
        )
    end
end
spawn(checkPressed())

I also get the error '11:53:33.494 - Spawn function requires 1 argument' in the last line