ติดปัญหาการ insert และ select identity (PHP AdoDB / sql server 2008)

<?php
$serverName = "localhost";
$connectionInfo = array("Database"=>"test","UID"=>"sa", "PWD"=>"123456");
$conn = sqlsrv_connect($serverName, $connectionInfo);
if( $conn === false )
{
    echo "failed connection";
}

			$tsql = "INSERT INTO Users_info (Username, Email) VALUES ('$Username', '$Email')";
			$stmt = sqlsrv_query( $conn, $tsql, array(), array( "Scrollable" => SQLSRV_CURSOR_KEYSET ));

			$UserID = '';  #$Userid select มาหลังจาก insert Users_info <--

			$tsql = "INSERT INTO [Users_Pass] ([UserID], [Password]) VALUES ('$Userid', '$Password')";
			$stmt = sqlsrv_query( $conn, $tsql, array(), array( "Scrollable" => SQLSRV_CURSOR_KEYSET ));
?>