Error while loading loop

Hello , i have created a loop field named ‘repeater’.
I have a nested link field in it.
I use the following code to generate my repeater field inside my custom post type single-page.

$fields = CFS()->get( 'repeater' );
foreach ( $fields as $field ) {
    echo $field['overview'];
}

I get the following error :
Warning: Invalid argument supplied for foreach() .

Can someone tell me what is wrong? And how can i use these fields in my HTML so can use them in a menu?

Thanks