Assuming you're talking about the Material Overrider presets, you need to make sure you have the assets installed. The Material Overrider lists the material paths its looking for when you select an override. You should make sure you have those materials.

It is also worth noting that the Futaprop is only designed to work with later DazV5-5 models. DazV5-5 introduced the futanari textures directly onto the character's body texture, allowing the futanari prop to not take up any additional memory. Trying to apply it to older models that don't have those modified body textures will cause problems.