edwin,
IIRC, standard 4.5 does not work with pg7.2 . You need to do a checkout out from development head of CVS.
Conversely, dotLRN and what-will-soon-be openACS 4.6 will not work with pg7.1
My suggestion is bite the bullet and stick with pg7.2 If this thread is anything to go by, the days of openACS and pg7.1 are numbered.