Warning: Illegal string offset in

Hi.
When I create a setting to hide the title (checkbox), I get error.
Warning: Illegal string offset 'hidepagetitle' in.
When I open the page in the admin and press the hidepagetitle button and update, error disappears and it works.

<h1 class="entry-title">
<a href="<?php the_permalink(); ?>" rel="bookmark">
<?php 
$hidepagetitle = rwmb_meta('dipost');

if ($hidepagetitle['hidepagetitle'] == false){
            the_title();
}
?></a></h1>

Why am I getting that error?
Thanks