Add custom image size not working

I want to add a custom image size to my child theme.

The base is the Penscratch theme, and it has it own image sizes defined:

function penscratch_setup() {

    /*  ...  */

    add_theme_support( 'post-thumbnails' );
    add_image_size( 'penscratch-featured', '400', '200', true );

    /*  ...  */
}

And if I made some changes here (base functions.php), everything work as it should, But the point is to make it done in child-Theme, I’m writing it the same way but for some reason it’s not working:

add_action( 'after_setup_teme', 'add_custom_img_sizes');

function add_custom_img_sizes()
{    
  add_theme_support( 'post-thumbnails' );
  add_image_size( 'category-thumbnail', '300', '200', true );
}

if I use then the ‘category-thumbnail’ in my template, it is displaying the full-sized image, not the cropped one, what is going wrong here?

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