Non capisco l'errore

[the_driver]

CIao a tutti, ho il seguente errore

Fatal error: Uncaught exception 'com_exception' with message 'Source: Microsoft JET Database Engine
Description: Could not find file '\desktop\server2go\server\apache\usb_analysis.mdb '.' in \server2go\htdocs\files\lib\conn_db.php:18 Stack trace: #0 \server2go\htdocs\files\lib\conn_db.php(18): com->open('Provider=Micros...') #1 \server2go\htdocs\index.php(13): open_db() #2 {main} thrown in \server2go\htdocs\files\lib\conn_db.php on line 18



posto il codice

<?php
/*Libreria utilizzata per la connessione al database ACCESS*/
/*Apertura Database*/
function open_db() {
    /*Libreria di connessione DB*/
    $path= "./";
    $db_name= "usb_analysis.mdb";
    $cn_string="Provider=Microsoft.Jet.OLEDB.4.0;";
    $dsource=$path.$db_name;
    $cn_string.="Data Source=$dsource;" ;
    $cn_string.="Jet OLEDB:Engine Type= 5;";
    if (!file_exists($dsource) ){
        die("Il database non esiste") ;
        return null;
    }
    else{
        $cn= new COM("ADODB.Connection");
        $cn->open($cn_string) ;
        echo "Connesso";
        return $cn;
    }
}

help! cosa sbaglio?