You can turn layers on and off in a DWF underlay.
By default, all layers in an attached DWF underlay are turned on. When using DWF underlays, it is usually convenient to turn off any unneeded layers to reduce the visual complexity of your work.
Use the DWFLAYERS command or the shortcut menu displayed when you right-click a selected DWF underlay to display the DWF layers dialog box.
You can use the Properties palette to determine whether any layers are turned off in a DWF underlay.