Advanced Translucent - Strange Shadow

[crankin]

Hi all. Does anyone know why the Advanced Translucent material gives this line of shadow? It doesn't appear with the other materials I've tried. Thanks. Corey.

[crankin]

This is the standard Translucent material - no line of shadow.

[crankin]

I've removed it by increasing the translucency, but this makes the shadows soft. Increasing the translucency is no good if you want hard shadow. If anyone knows what causes this line please let me know how to get rid of it. Thanks.

[crankin]

Interior lighting mode has removed it. If anyone has any ideas on how to remove if without using interiior mode I'd be glad to hear them. Cheers.