THM 125c 1995 Pont Sunfire trans

I recently overhauled my THM 125c auto trans due to bad reverse clutches.
So I decided to rebuild the whole tran.
After installing it back on car, and adding trans oil, done a run test on reverse
and forward with car off ground. Both th drive and reverse works ok but after
setting the car on ground I notice that in PARK, the car still rolls.
Dropped the pan and checked the Parking Pawl...in good condition...the bullet
and linkage, working as designed and the Pawl's tooth locks into the drum gear
(I don't know what it's called).
With the pan still off I manually rotated the tires while at the same time checking movement of the gear (gear did not move while Pawl was locked on).
I tried both axles (tires) and they both turned while the gear maintane itself
in a locked position.

question...where did I go wrong? what did I not do? how can I fixed this
problem? do I have to drop the tranny and if I do what section of the trans
do I have to shoot for to look for the problem?