Completely stuck - cannot get pgcrypto to work.

Hi all.
   I have spent all afternoon trying to fix this problem and I am
getting nowhere.

I did a fresh install of Redhat 7.3, then installed Postgres 7.3.2.
The problem I have is no matter what I try, I get "ERROR:  Load of file
/usr/local/pgsql/lib/pgcrypto.so failed:
/usr/local/pgsql/lib/pgcrypto.so: undefined symbol: px_get_random_bytes"

Can anyone help me resolve this problem ?

The exact commands I used to install and configure postgres are :

  ./configure
   make
   make install
   adduser postgres
   mkdir /usr/local/pgsql/data
   chown postgres /usr/local/pgsql/data
   su - postgres
   /usr/local/pgsql/bin/initdb -D /usr/local/pgsql/data
   /usr/local/pgsql/bin/postmaster -D /usr/local/pgsql/data >logfile 2>&1 &

and :
  cd ./contrib/pgcrypto/
changed makefile to use "dev".
make
make install
make installcheck
all tests fails.

If however, I dont change the makefile, i.e. I leave it using "silly",
everything works!!!!

What am I doing wrong ?

Richard