Twitter oAuth Connection issue - php

Question

I am doing Login with twitter in my application and using Twitter oAuth. I am placing proper consumer key and proper consumer secret key and valid callback url still having a error
Could not connect to Twitter. Refresh the page or try again later.
so what should I do now. couldn't trace out what is causing the trouble.
My index file
<?php
/**
* User has successfully authenticated with Twitter. Access tokens saved to session and DB.
*/
/* Load required lib files. */
session_start();
require_once('oauth/twitteroauth.php');
require_once('twitter_class.php');
if(isset($_GET['connect']) && $_GET['connect'] == 'twitter'){
$objTwitterApi = new TwitterLoginAPI;
$return = $objTwitterApi->login_twitter($_GET['connect']);
if($return['error']){
echo $return['error'];
}else{
header('location:'.$return['url']);
exit;
}
}
?>
My callback.php
<?php
session_start();
require_once('oauth/twitteroauth.php');
require_once('twitter_class.php');
if (isset($_REQUEST['oauth_token']) && $_SESSION['oauth_token'] !== $_REQUEST['oauth_token']) {
$_SESSION['oauth_status'] = 'oldtoken';
header('Location: destroy.php');
}else{
$objTwitterApi = new TwitterLoginAPI;
$connection = $objTwitterApi->twitter_callback();
if( $connection == 'connected'){
header('Location: index.php?connected=Y');
exit;
}else{
header('Location: index.php?connected=F');
exit;
}
}
Help me on this hence i am new to this couldn’t trace out the actual problem.
PS: in oAuth there is always a blank response if curl