PDO ODBC Virtuoso No Work but No Error

<?php

try { $dbc = new PDO('odbc:virtuoso','dba','dba'); }
catch (PDOException $e)
 {
    logError('Failed to connect to database: ' . $e->getMessage());
    exit(1);
  }

try
{
  $dbc->exec("USE studies;");
  $sql = "SELECT * FROM studies;";
  $rs = $dbc->query($sql);
  print_r($rs);
}
catch (PDOException $e)
{
  print "Failed SQL: " . $e->getMessage();
}

  //foreach ($dbc->query($sql) as $row)
  //{
  //  print $row['id'] .' - '. $row['description'] . '<br />';
  //}

print "Hey dude..\n";