Exporting Mssql Table Data into csv file using php

When I run php script to export MSSQL server table data I got this error message:

Warning: mssql_query() [function.mssql-query]: message: Unicode data in a Unicode-only collation or ntext data cannot be sent to clients using DB-Library (such as ISQL) or ODBC version 3.7 or earlier. (severity 16) in C:\Program Files\Apache Software Foundation\Apache2.2\htdocs\Newitemtest\csv3.php on line 22

Can anyone point me in correct way? Thank you so much in advance.

Below is my php script

<?php
    $myServer = "****";
    $myUser = "**";
    $myPass = "****";
    $myDB = "***";

    $dbhandle = mssql_connect($myServer, $myUser, $myPass)
            or die("Couldn't connect to SQL Server on $myServer"); 

        $selected = mssql_select_db($myDB, $dbhandle)
            or die("Couldn't open database $myDB"); 

        $query = "SELECT * ";
        $query .= "FROM Item ";
        $result = mssql_query($query, $dbhandle);

    while ($l = mssql_fetch_array($result, MSSQL_ASSOC)) {
    foreach($l AS $key => $value){
        $pos = strpos($value, '"');
            if ($pos !== false) {
                $value = str_replace('"', '\"', $value);
            }
            $out .= '"'.$value.'",';
    }
    $out .= "\n";
    }
    mssql_free_result($result);
    mssql_close($dbhandle);

    header("Content-type: text/x-csv");
    header("Content-Disposition: attachment; filename=export.csv");
    echo $out;
?>