How to switch track?

I'm working on a switch track doohickey, and I got the button to work by if you click it, it will change its BoolValue Child, Curve to true, then this script, if the BoolValue is true, it will do a function, but It won't work. Please help.

curve = script.Parent.Button.Script.Curve
track1 = script.Parent.Turn.Turn2.M2
track2 = script.Parent.Turn.Turn2.M3
un1 = script.Parent.Straight.yep
un2 = script.Parent.Script.yep2

while true do
    if curve.Value == true then
        changeTrackPos()
    else
        wait()
    end

end

function changeTrackPos()
    print('positive rate')
    if un1.CanCollide and un2.CanCollide == false then
        un1.CanCollide = true
        un2.CanCollide = true
        un1.Transparency = 0
        un2.Transparency = 0
    else
        un1.CanCollide = false
        un2.CanCollide = false
        un1.Transparency = 0.5
        un2.Transparency = 0.5
     local children1 = track1:GetChildren()
for i = 1, #children1 do
    if children1[i].CanCollide == false then
    children1[i].CanCollide = true
children1[i].Transparency = 1
    else
        children1[i].CanCollide = false
        children1[i].Transparency = 0.5
local children2 = track2:GetChildren()
for a = 2, #children2 do
if children2[a].CanCollide == false then
    children2[a].CanCollide = true
children2[a].Transparency = 1
else
    children2[a].CanCollide = false
    children2[a].Transparency = 0.5
end
end
    end
end
    end
    end