my function only works once for my touch function, what am I doing wrong?

script.Parent.DamagePart.Touched:Connect(function(p)
    if script.Parent.CanDamage.Value == true then
    script.Parent.CanDamage.Value = false
    p.Parent.Humanoid:TakeDamage(20)
    script.Parent.CanDamage.Value = true
    end
end)

You never set the CanDamage value back to true, so the script doesn't get the heads up to run again. You can add a wait if you want to so they don't get damaged as rapidly if you want. This will set it back to true right after the character takes the 20 damage.

Hope this helps!