Some undefined function errors

Hi all.

Recently, I wrote an email about the problem I was having with some Postgres functions that when those functions were
called,I received the following error: "Call to undefined function <function_name>". 

After some answers, I decided to rebuild a brand new linux virtual machine with Apache + PHP + Postgres, but I still
getthis annoying error messege with some functions like pg_prepare() and pg_escape_string(). 

I compiled Postgres with --without-readline option.
I compiled PHP with --with-apxs2=/usr/local/apache2/bin/apxs and --with-pgsql=/usr/local/pgsql/

And the compilation process has no errors.

What am I doing wrong? Do I have to change something in php_config.h file? If so, what do I have to change?

Thank you.