Shonner,

Try reducing the Max Brightness setting on the GI Shadow Catcher if your plane is showing up in the render. That setting gives GI Shadow Catcher a reference of where the full lighting is. Anything below that it considers to be in shadow, anything above is lit. The shadow catching plane is showing up because it thinks the light is too dim. If you reduce Max Brightness, it will expect that level and the plane won't show.

Regards,

Eric Winemiller
Digital Carvers Guild
Carrara and LightWave plug-ins