setParameter question

First you need to specify the layer with getLayer() or findLayers() and then use the setParameter.

function subLayer1MuteChanged()
  local layer = this.parent:findLayers(true, "SubLayer1_1")[1]
  if layer then
    layer:setParameter("LayerMute", Sub1Mute)
  end
end

defineParameter("Sub1Mute", nil, false, subLayer1MuteChanged)