is_active_sidebar() not working

Try this in your functions.php

function your_widget(){

register_sidebar(array( 
    'name' => 'Footer Column 2',
    'id' => 'footer-column-2', // I also added the ID but doesn't work 
    'before_widget' => '<div id="%1$s" class="omc-footer-widget %2$s">',    
    'after_widget' => '</div>', 
    'before_title' => '<h4>',   
    'after_title' => '</h4>'   
));

}

add_action( 'widgets_init', 'your_widget' );

Call in footer.php with the ID.

<?php if ( is_active_sidebar( 'footer-column-2' ) ) : ?>    

    <div class="omc-footer-widget-column">  

            <?php dynamic_sidebar( 'footer-column-2' ); ?>

    </div><!--- /second-footer-column -->

<?php endif; ?>