Debugging Yii-users authentication on AWS Elastic Beanstalk

Question

I've hosted my Yii webapp on AWS. The login isn't working and redirects to the logged out homepage. Debugging on AWS is proving difficult.

My app implements Yii-users for the authentication system and the following controller acton is run for the login view:

    public function actionLogin()
{
    if (Yii::app()->user->isGuest) {

        $model=new UserLogin;

        // collect user input data
        if(isset($_POST['UserLogin'])){
            $model->attributes=$_POST['UserLogin'];
            // validate user input and redirect to previous page if valid
            if($model->validate()) {                
                $this->lastViset();
                if (Yii::app()->user->returnUrl=='/index.php'){
                    $this->redirect(Yii::app()->controller->module->returnUrl);
                } else {
                    $time = date('h:i:s A');
                    mail('my-email@gmail.com','Debugging',"BP3 $time");
                    $this->redirect(Yii::app()->user->returnUrl);
                }
            }
        }
        // display the login form
        $this->render('/user/login',array('model'=>$model));

    } else {
        $this->redirect(Yii::app()->controller->module->returnUrl);
    }
}

The code runs OK the POST data is being passed, the problem appears to be with the $model->validate() not evaluating to true. I believe this to be the case as I've followed which parts of the login action run "if($model->validate())" runs, but the code within the loop doesn't making me think it hasn't evaluated to true.

The UserLogin model is like so:

<?php

/**
 * LoginForm class.
 * LoginForm is the data structure for keeping
 * user login form data. It is used by the 'login' action of 'SiteController'.
 */
class UserLogin extends CFormModel
{
public $email;
public $password;
public $rememberMe;

/**
 * Declares the validation rules.
 * The rules state that username and password are required,
 * and password needs to be authenticated.
 */
public function rules()
{
    return array(
        // username and password are required
        array('email, password', 'required'),
        // rememberMe needs to be a boolean
        array('rememberMe', 'boolean'),
        // password needs to be authenticated
        array('password', 'authenticate'),
    );
}

/**
 * Declares attribute labels.
 */
public function attributeLabels()
{
    return array(
        'rememberMe'=>UserModule::t("Remember me next time"),
        'username'=>UserModule::t("email"),
        'password'=>UserModule::t("password"),
    );
}

/**
 * Authenticates the password.
 * This is the 'authenticate' validator as declared in rules().
 */
public function authenticate($attribute,$params)
{
    if(!$this->hasErrors())  // we only want to authenticate when no input errors
    {
        $identity=new UserIdentity($this->email,$this->password);
        $identity->authenticate();
        switch($identity->errorCode)
        {
            case UserIdentity::ERROR_NONE:
                $duration=$this->rememberMe ? Yii::app()->controller->module->rememberMeTime : 0;
                Yii::app()->user->login($identity,$duration);
                break;
            case UserIdentity::ERROR_EMAIL_INVALID:
                $this->addError("username",UserModule::t("Email is incorrect."));
                break;
            case UserIdentity::ERROR_USERNAME_INVALID:
                $this->addError("username",UserModule::t("Username is incorrect."));
                break;
            case UserIdentity::ERROR_STATUS_NOTACTIV:
                $this->addError("status",UserModule::t("You account is not activated."));
                break;
            case UserIdentity::ERROR_STATUS_BAN:
                $this->addError("status",UserModule::t("You account is blocked."));
                break;
            case UserIdentity::ERROR_PASSWORD_INVALID:
                $this->addError("password",UserModule::t("Password is incorrect."));
                break;
        }
    }
}
}

I don't understand what would not work with this code on AWS that works fine on a shared/local environments. I'm using the Elastic Beanstalk environment and have overridden several settings of the php.ini file with the following:

files:
  "/etc/php.d/project.ini" :
    mode: "000644"
    owner: ec2-user
    group: ec2-user
    content: |
        error_reporting = E_ALL & ~E_STRICT & ~E_NOTICE & ~E_WARNING
        display_errors = On
        post_max_size = 32M
        enable_dl = On

How should I go about debugging this code on AWS? Admittedly my knowledge of Yii-users is not as good as it should be.