CustomPress 'if' custom field is ticket 'then'

Hi there. I am using Custompress to add a custom field to my regular WP posts. The field is actually a check box, and the idea is that if the checkbox is ticked, then it does not show the featured image in the actual post (as the post is going to show an infographic so 2 images is overkill).

So I have the code below which is meant to add 'display:none;' to the featured image 'div' if the custom field box is ticked:

<div class="featuredimage" <?php if( get_post_meta($post->ID, '_ct_text_513016b86c9b7', true) ) { ?> style="display:none;" <?php } ?>>

I am fairly sure this was working the other day, but it doesn't seem to be now working now and 'display:none;' is always the case. Do you know if there is anything wrong with the snippet?

Many thanks,
Craig