Include a class containing a use command in another class

I have two php files: facebook.php (for getting user data) and MyClass.php for providing a restfull service. facebook.php

<?php                   
        require_once( '../libs/facebook/src/Facebook/HttpClients/FacebookHttpable.php');
        require_once( '../libs/facebook/src/Facebook/HttpClients/FacebookCurl.php' );
        require_once( '../libs/facebook/src/Facebook/HttpClients/FacebookCurlHttpClient.php' );

        require_once( '../libs/facebook/src/Facebook/Entities/AccessToken.php' );
        require_once( '../libs/facebook/src/Facebook/Entities/SignedRequest.php' );

        require_once( '../libs/facebook/src/Facebook/FacebookSession.php' );
        require_once( '../libs/facebook/src/Facebook/FacebookRedirectLoginHelper.php' );
        require_once( '../libs/facebook/src/Facebook/FacebookRequest.php' );
        require_once( '../libs/facebook/src/Facebook/FacebookResponse.php' );
        require_once( '../libs/facebook/src/Facebook/FacebookSDKException.php' );
        require_once( '../libs/facebook/src/Facebook/FacebookRequestException.php' );
        require_once( '../libs/facebook/src/Facebook/FacebookOtherException.php' );
        require_once( '../libs/facebook/src/Facebook/FacebookAuthorizationException.php' );
        require_once( '../libs/facebook/src/Facebook/GraphObject.php' );
        require_once( '../libs/facebook/src/Facebook/GraphSessionInfo.php' );



        use Facebook\HttpClients\FacebookHttpable;
        use Facebook\HttpClients\FacebookCurl;
        use Facebook\HttpClients\FacebookCurlHttpClient;

        use Facebook\Entities\AccessToken;
        use Facebook\Entities\SignedRequest;

        use Facebook\FacebookSession;
        use Facebook\FacebookRedirectLoginHelper;
        use Facebook\FacebookRequest;
        use Facebook\FacebookResponse;
        use Facebook\FacebookSDKException;
        use Facebook\FacebookRequestException;
        use Facebook\FacebookOtherException;
        use Facebook\FacebookAuthorizationException;
        use Facebook\GraphObject;
        use Facebook\GraphSessionInfo; 
    function getUserData($token){


    // init app with app id and secret
    FacebookSession::setDefaultApplication( FB_APP_ID,FB_APP_SECRET );

    // If you already have a valid access token:
    $session = new FacebookSession($token); // 'access-token'



    /*
    // If you're making app-level requests:
    $session = FacebookSession::newAppSession();
    */

    // To validate the session:


    try {

    $session->validate();

    } catch (FacebookRequestException $ex) {
    // Session not valid, Graph API returned an exception with the reason.
    echo $ex->getMessage();

    return false;
    } catch (\Exception $ex) {

    // Graph API returned info, but it may mismatch the current app or have expired.
    echo $ex->getMessage();

    return false;
    }


    if($session) {

    try {

        $user_profile = (new FacebookRequest( $session, 'GET', '/me'))->execute()->getGraphObject()->asArray(); //(GraphUser::className());

        $id = $user_profile['id'];
        $user_profile['image'] = 'https://graph.facebook.com/'.$id.'/picture?width=200';



        // print profile data
        echo '<pre>' . print_r( $user_profile, 1 ) . '</pre>';

        return $user_profile;

        // print logout url using session and redirect_uri (logout.php page should destroy the session)
        //echo '<a href="' . $helper->getLogoutUrl( $session, 'http://yourwebsite.com/app/logout.php' ) . '">Logout</a>';

        //echo "Name: " . $user_profile->getName();

    } catch(FacebookRequestException $e) {

        echo "Exception occured, code: " . $e->getCode();
        echo " with message: " . $e->getMessage();

        return false;

    }
    }



    }



    ?>

      

        
        
        
      

    

and MyClass.php is

<?php


/**
* Class to manage user data
* 
*
* 
* 
*/
class DbHandler {

function __construct() {

    include_once '../../../include/Facebook.php';

}

/**
* Get user data from facebook
* @param user key
* @return user data if exist else false
*/
public function facebookSignIn($token){


    $fbUserData = getUserData($token);

    if($fbUserData == false) echo 'no user found';
    else print_r($fbUserData);

}


}
?>

      

        
        
        
      

    

the line (include_once '../../../include/Facebook.php';) is correct because if I comment out these lines of code the script works

    use Facebook\Entities\AccessToken;
    use Facebook\Entities\SignedRequest;

    use Facebook\FacebookSession;
    use Facebook\FacebookRedirectLoginHelper;
    use Facebook\FacebookRequest;
    use Facebook\FacebookResponse;
    use Facebook\FacebookSDKException;
    use Facebook\FacebookRequestException;
    use Facebook\FacebookOtherException;
    use Facebook\FacebookAuthorizationException;
    use Facebook\GraphObject;
    use Facebook\GraphSessionInfo; 

      

        
        
        
      

    

Perhaps I don't understand the "use" command what is the problem? Thanks for your attention.