An invalid parameter was passed to sqlsrv_query

Hi all,

I have installed php 5.3.13 on a Web Role (windows Azure) and it uses sql azure as database. Following is my code:

dbConnectDB.php
---------------------------

$uid = myid@myserver;
$pwd = "mypassword";
$dbname = "mydbname";
$serverName = "tcp:myserver.database.windows.net,1433";
$connectionInfo = array("UID" => $uid, "PWD" => $pwd, "Database" => $dbname);
$conn = sqlsrv_connect($serverName, $connectionInfo);
if($conn == false){
     FatalError("Failed to connect...");
}
it seems that $conn is not false.
index.php
---------------------------
include_once 'dbConnectDB.php';
include_once 'session.php';
 $login_query = "SELECT * FROM admins WHERE username = ? and password = ?";  
 $params = array("theUsername", "thepassword");
 $login_result = sqlsrv_query($conn, $login_query,  $params);
 if ($login_result == false){
    die( print_r( sqlsrv_errors(), true));
 }
 
 $login_object = sqlsrv_fetch_object( $login_result);
Here everything works fine and I can fetch the resultset.
but If I execute same query in session.php it generates:
 "An invalid parameter was passed to sqlsrv_query"
as you see on the top of index.php I have inclueded both dbConnectDB.php and session.php so it should work
in session.php as well.
Thanks for your advice.