My daughter's Stanza had a similar problem.
Is there a manual-disengagement button (red?) just in front of the shift
lever?  Did you try pushing this down while trying to move the shift?

In my daughter's case, the problem was caused by interlocks (trouble is,
it's been a while, and I can't remember exactly which one...sorry).  I
took off the plastic cover through which the shift lever protrudes, and
some more bits (I think) to reveal what exactly is going on when you try
to move the lever.  As I recall, there's a linkage attached to the
thumb-button (at the top of the lever) that will not allow the lever to
be moved unless a solenoid-operated stop is drawn out of the way.  That
solenoid in my case was not operating, and the reason was some obscure
interlock which was not getting enabled (seat switch?, brake switch? I
forget)  I overrode it with a bypass wire to confirm the diagnosis, then
tracked down the actual fault and fixed it.

Good luck!

Geoff.