[LAU] Ardour track question

[Jonathan E. Brickman]

 I think I am missing some essential understanding of Ardour.  I have
Ardour set up in default manner (Fedora 13), one Master bus, and have
added one track.  The input of the one track has been successfully set
to Linux Sampler; when I get sound out of LS, the meter in the track
moves nicely.  However, when I change the metering point in the track
from "input" to either "pre" or "post", the meter doesn't move at all. 
(Obviously there are more consequences too, but this is the boil-down.) 
There are no plugins in all.  Recording does work, the wave data is
clearly visible.  What am I doing wrong?

J.E.B.