Thumbnail Size: No thumbnails, only full-image

Hey, really nice widget, you’ve created. Well done!

I have a weird problem: Independently which “Thumbnail Size” I choose, it’s always the full-version. Without doubt, that’s a bit too much for a widget-picture ?? Furthermore I use a custom size, which is listed in your thumbnail-tab, but even that size doesn’t work.

In your functions.php you have the get_the_post_thumbnail, but as far as I can see, everything seems correct.

If I use my custom image size in the functions.php or e.g. in the plugin WordPress Popular Posts (also for the widget), everything works fine.

Do you have any idea to solve this or to look somewhere else?

Thanks and best regards from Berlin
Sebastian