add_image_size child theme not working

I am trying to add a few custom image sizes inside the functions.php of the child theme. I add the code below and then run Regenerate Thumbnails on an image, but it doesn’t create any of my custom image sizes. I know the plugin is working because if I delete one of the existing thumbs, it recreates it.
Am I doing something wrong?

function custom_image_sizes() {
	add_image_size("custom-thumb", 218, 125, true);
	add_image_size("custom-large-thumb", 290, 166, true);
	add_image_size("custom-medium", 532, 304, true);
	add_image_size("custom-slider", 700, 400, true);
}
add_action('after_setup_theme', 'custom_image_sizes', 11);

Hi

I’ve tested you’re code in child theme and works fine on my side: http://screencast.com/t/tdFHg1x6cI I am not sure why this code doesn’t work on your side but you can try to remove any other customizations from child theme, or also try to deactivate the child theme and insert the code in functions.php in parent theme.

Thanks!