frontpage & output picture, php error

I am using EXACT the method described in your own documentation to show a single image:

<?php
    $images = rwmb_meta( 'xximagefieldxx', array( 'limit' => 1 ) );
    $image = reset( $images );?>
<img src="<?php echo $image['url'];?>" width="xx" height="xx>

but getting a PHP error:
WARNING: reset() expects parameter 1 to be array, string given in var/www/xxx/ eval()'dcode on line 3

So what's wrong? Documentation?

It's worth mentioning that currently only one picture is stored in the field...
Seems reset( $images ) refers to the same Image ID (the only existing one), maybe this is the error.
The picture itself is printed out to html.

Any advice?