samhal - Hmm. Well I'm rendering at the moment so I can't check, but...[That is becoming my all-purpose excuse these days.]

My understanding was that each Shadow Cam was linked to a particular light; that camera is used to render the shadows from that light, so they have to match. There is al least one problem figuring out which Shadow Cam goes with which Light. (Poser 8 may help there, or it's just been that I'm using a scene where the vendor nicely named the Shadow Cams to match the Lights.] Also, while looking through the Shadow Cam, you probably want to set the Dials Panel to show the controls of the corresponding Light. Then, I think, things should work as you expect. Maybe.

Whichway

P.S. - I suppose it's possible that if the light has Shadows turned off, there is no corresponding Shadow Cam.