Problem with changing rotating images in 2011 theme

I am struggling and I hope someone can help me out. I am trying to change the rotating images in the 2011 theme. I am using the step by step instructions found here: https://wpti.ps/functions/replace-default-header-image-twenty-ten-theme/

In a nutshell, I created a child theme directory (Child2011) under the themes directory, added the index.php file from the original 2011 theme to the child directory, and created two files: style.css, and functions.php.

Here is the code that is each.

(functions.php)

?php
// REMOVE TWENTY ELEVEN DEFAULT HEADER IMAGES
function wptips_remove_header_images() {?unregister_default_headers( array('wheel','shore','trolley','pine-cone','chessboard','lanterns','willow','hanoi'));
}
add_action( 'after_setup_theme', 'wptips_remove_header_images', 11 );
?>

(style.css)

<?php
// REMOVE TWENTY ELEVEN DEFAULT HEADER IMAGES
function wptips_remove_header_images() {?unregister_default_headers( array('wheel','shore','trolley','pine-cone','chessboard','lanterns','willow','hanoi'));
}
add_action( 'after_setup_theme', 'wptips_remove_header_images', 11 );
?>

At this point my expectation is that when I activate the child theme I should get the template with the rotating images removed, but instead the child theme is broken and if I activate it I have to go into my FTP to remove it to even get back to the wp-admin area.

Thoughts?

Thanks for your help.