apache virtual host with laravel 5 "Internal error 500"

I want to learn laravel, and recently installed a fresh copy laravel on an amazon ec2 instance through composer composer create-project laravel/laravel laravel-app with apache2, and php installed. I configure the confd file to change the document root to laravel-folder/public, when i try to go to the public ip address it show a server 500 error.

<VirtualHost *:80>
    # The ServerName directive sets the request scheme, hostname and port that
    # the server uses to identify itself. This is used when creating
    # redirection URLs. In the context of virtual hosts, the ServerName
    # specifies what hostname must appear in the request's Host: header to
    # match this virtual host. For the default virtual host (this file) this
    # value is not decisive as it is used as a last resort host regardless.
    # However, you must set it for any further virtual host explicitly.

    #elastic IP address
    ServerName 42.66.33.52 
    ServerAdmin webmaster@localhost
    DocumentRoot laravel-app/public

    <Directory laravel-app/public>
    DirectoryIndex index.php
    Options -Indexes +FollowSymLinks +MultiViews
    AllowOverride All
    Order allow,deny
    Allow from all
    Require all granted

    </Directory>

    # Available loglevels: trace8, ..., trace1, debug, info, notice, warn,
    # error, crit, alert, emerg.
    # It is also possible to configure the loglevel for particular
    # modules, e.g.
    #LogLevel info ssl:warn

    ErrorLog ${APACHE_LOG_DIR}/error.log
    LogLevel warn
    CustomLog ${APACHE_LOG_DIR}/access.log combined

    # For most configuration files from conf-available/, which are
    # enabled or disabled at a global level, it is possible to
    # include a line for only one particular virtual host. For example the
    # following line enables the CGI configuration for this host only
    # after it has been globally disabled with "a2disconf".
    #Include conf-available/serve-cgi-bin.conf

I've tried chmod 777 to the entire laravel folder and changed the url in app.php to 42.66.33.52, and it still showing the same error. I'm new to laravel, and I hope someone can point me to the right direction. I've host other PHP website from this server without using laravel framework and it is function normally.

via Chebli Mohamed