Perhaps the park your are trying to enter doesn't allow Maximas.  Try
entering on foot.  :-)

Seriously, my 2000 max has a switch on the shifter that must be
pressed in before the trans can be placed in reverse or park.  If the
94 has a similar configuration you might try pressing the switch extra
hard with a wiggle while trying to shift to park.  If that does the
trick there is likely somthing wrong with the nechanism on the
shifter.  The only other cause of your problem that I can think of
would be the tran$mi$$ion.  Good luck!

Your shift lock solenoid and/or controller unit may be bad.  A pain in the
butt to fix unless you have a shop manual and a multimeter to test the
circuit.  My 94 doesn't have the lock release button, but my 90 GXE does.
Don't know why! I replaced both the shift lock solenoid and controller on my
90 GXE.
Can you get the key out of the ignition lock??  I don't think it will let
you if it doesn't go into Park.
I'm gonna guess it's your controller unit.

Chris
90 & 94 GXE's