ERROR CONNECTION POSTGRES 8.1

We have problem connecting to postgres 8.1 database

Example

#include <stdio.h>

main ()
{
EXEC SQL BEGIN DECLARE SECTION;
EXEC SQL END DECLARE SECTION;

EXEC SQL CONNECT TO tcp:postgresql://localhost/basedati_latin AS
connection1 USER root;
EXEC SQL CONNECT TO tcp:postgresql://localhost/basedati_arg AS
connection2 USER root;
EXEC SQL SET CONNECTION connection1;
EXEC SQL DISCONNECT connection1;
EXEC SQL DISCONNECT connection2;
}

We have syntax error when compiling this (syntax used in 8.1 documentation)
If we write

#include <stdio.h>

main ()
{
EXEC SQL BEGIN DECLARE SECTION;
EXEC SQL END DECLARE SECTION;

EXEC SQL CONNECT TO tcp:postgresql://localhost/basedati_latin AS
connection1 USER root;
EXEC SQL CONNECT TO tcp:postgresql://localhost/basedati_arg AS
connection2 USER root;
EXEC SQL SET CONNECTION TO connection1;
EXEC SQL DISCONNECT connection1;
EXEC SQL DISCONNECT connection2;
}

we haven't compiling errors but we obtain [4-1] ERROR: unrecognized
configuration parameter "connection".
Can you help us
Thanks in advance

--
Best regards,
Doc. Edoardo Innocenti
System Administrator
Lulli S.r.l, ITALY
Tel: +39.055.721365
Fax: +39.055.721637