(PHP/Postgresql) Call a function which returns void?

I'm getting crazy trying to call, inside PHP code, a function that returns void, with pg_prepare/pg__execute...

$result = pg_prepare($dbconn, "",'SELECT * FROM dungeonasdb.crea_personaggio( "$nome", "$descrizione", "$email", "$password")');
$result = pg_execute($dbconn, "", NULL ) or die('Query creazione fallita');

Is there any settings of pg_prepare/pg_execute that I do wrong? Thanks