php - MSSQL using PDO to connect -

i trying connect mssql server on mac through pdo_dblib. have freetds.conf updated host want connect. phpinfo tells me have driver hooked , go. below code wrote test if can connect server.

<?php   $servername = "ip";   $port = "port";   $username = "username";   $password = "password";   $mydb = "database";   try {      $conn = new pdo("dblib:dbname=$mydb;host=$servername:$port", "$username", "$password");       // set pdo error mode exception      $conn->setattribute(pdo::attr_errmode, pdo::errmode_exception);      echo "connected successfully";    }   catch(pdoexception $e)   {   echo "connection failed: " . $e->getmessage();   } ?> 

however error:

connection failed: sqlstate[] (null) (severity 0)

i tried using sql developer connect mssql server , worked. have been trying solve problem whole day. might problem? thanks!

remove quotes variables in connection string -

 $conn = new pdo("dblib:dbname=$mydb;host=$servername:$port", $username, $password);