pg_ctrl stop problems (psql 8.2.5)

I am running postgresql 8.2.5 on Solaris 10.  When I try to shut down postgres using

pg_ctrl -D datafile stop

it does not shutdown.    Does anyone know why this is, or what files pg_ctrl access to determine

the shutdown process.  We have tried deleting a pgsql semaphore file located in tmp.  This did not help.  Any help is appreciated.