Error with clouds with the mobile weather system

I'm getting an issue with the mobile weather system (C#)

I have a blank scene and create the weather system, clouds do not work and I have the following error in the console.

Screenshot 2016-02-05 18.12.27

The demo scene works. Is there something I'm missing?

The error is referring to the following in UniStormMobileWeatherSystem.cs :

          heavyCloudsLayerLightComponent.materials[ materialIndex ].SetTextureOffset( CloudA, uvOffsetHeavyA );

heavyCloudsLayerLightComponent.materials[ materialIndex ].SetTextureOffset( CloudB, uvOffsetHeavyB );

heavyCloudsLayerLightComponent.materials[ materialIndex ].SetTextureOffset( CloudC, uvOffsetHeavyC );