Blank child theme - functions.php problem

Question

I've created a child theme, and moved all the modifications I had in the parent theme functions.php into the child theme's functions.php. Now if I preview the theme, it is blank.

I've got three things - changing the number of tags displayed in the cloud, hiding a product category and displaying a Google books preview.

I can't see any errors in this code, and it works when it's in the parent.

I would appreciate any help, I'm totally stuck!

<?php

function change_tag_cloud_widget() {
    $args['number'] = 15;
    return $args;
}
add_filter( 'widget_tag_cloud_args', 'change_tag_cloud_widget' );

add_action( 'pre_get_posts', 'custom_pre_get_posts_query' );

function custom_pre_get_posts_query( $q ) {

if ( ! $q->is_main_query() ) return;
if ( ! $q->is_post_type_archive() ) return;
if ( ! is_admin() ) {

$q->set( 'tax_query', array(array(
'taxonomy' => 'product_cat',
'field' => 'slug',
'terms' => array( 'hands-on' ), // Don't display products in the hands-on category on the shop page
'operator' => 'NOT IN'
)));
}

remove_action( 'pre_get_posts', 'custom_pre_get_posts_query' );

    }

add_shortcode('gbooks', 'sc_embed_google_books');
function sc_embed_google_books( $atts ){
    extract(shortcode_atts(array(
            "id" => '',
            "width"  => '600',
            "height" => '900',
    ), $atts));
    return '<script type="text/javascript" src="http://books.google.com/books/previewlib.js"></script>
    <script type="text/javascript">
    GBS_insertPreviewButtonPopup("'.$id.'", '.$width.','.$height.');
    </script>';
}


function get_google_tag( $isbn_metadata ) {
return (
    /* '<span class="post-meta-key">Preview: </span>' . */
    '<script type="text/javascript" src="http://books.google.com/books/previewlib.js"></script>' .
    '<script type="text/javascript">' .
    'GBS_insertPreviewButtonPopup(\'ISBN:' . $isbn_metadata . '\');' .
    '</script>'
);
}

?>

Answer 1

I've created a child theme, and moved all the modifications I had in the parent theme functions.php into the child theme's functions.php

Don't move all the functions from the parent theme into the child theme, just add the modifications to the child theme and leave the parent functions.php as it came with the theme.

You are most likely loading the functions twice as a result.

Unlike style.css, the functions.php of a child theme does not override its counterpart from the parent. Instead, it is loaded in addition to the parent’s functions.php. (Specifically, it is loaded right before the parent’s file.)

http://codex.wordpress.org/Child_Themes#Using_functions.php