Quick noobie question:

I have a forest scene with characters in it and obviously trees. I set a basic light set and now I'm trying to render it. The problem is I only seem to get cast shadows when I have no ready props/scenes (when it's just the characters on the default ground).

I have everything checked with "cast shadow" and it's also checked in my render settings. So I'm not sure I understand why it's no longer casting any shadows (I just get normal shades). In the preview it looks like I see things casting shadows but it all disappears once I render.

What do I have to do to make all the characters/props cast shadow in the firefly scene?