[Paraview] zoom in and zoom out in Paraview

[wang]

Dear Paraview users,

I want to use Paraview to make nice movies. One thing I want to do is to 
use "interpolate camera location" to zoom my object in and out. But it 
seems don't do what it should do. I tried to define camera position in 
x,y,z coordinates but these have no effect.  No matter what values or 
combination of values of x,y,z the object remains the same. It does not 
go away or come near.

Does any one know about this or has a script to do this? Any hint is 
more than welcome!

Thanks!
Xueli