unspecified function pg_pconnect() error ?

[JayasankarGNair]

Hi,
         When I try to login to my pop3 server wchich is a separate
machine...
I get the error " Call to unsupported or undefined function pg_pconnect() in
./lib/db.lib on line 322"

When I checked up the file ../lib/db.lib I found the command

return{{$db=pg_pconnect{$dbconnectstring}}};


What does this mean?
      I have IMP-2.0.11-1 installed with
1.apache-1.3-14-2.6.2
2.mod-php3-3.0.15-1tr
3.horde-core-1.0.10-1
4.postgrespl-6.5.3-6
5.Openldap-1.2.10-4
6.Mysql-3.22.32-1

on my Red hat linux 6.1 machine.I needed to get mails from my pop3 server
through the IMP server.

I'm getting the /horde/index.php3 page correct when I go to
http://ipaddress/horde/

But when I click on 'Imp' in the index.php3 , I'm getting a "DOCUMENT
CONTAINS NO DATA "error.

Please Help ...
thanks in advance...
jayasankar