在WordPress中上传文件时“上传测试失败”

So I'm busy making my own theme in WordPress and am busy with the settings page:

I'm preparing the handler that will save the file to the media library. This is the handler code:

function handle_logo_upload() {
    if ( !function_exists( 'wp_handle_upload' ) ) {
        require_once( ABSPATH . 'wp-admin/includes/file.php' );
    }
        $upload_overrides = array( 'test_form' => false );
        $uploadedfile = $_FILES['upload_logo']['name'];
        $movefile = wp_handle_upload( $uploadedfile, $upload_overrides );
        print_r($movefile);
        wp_die();
        if ( $movefile ) {
            $wp_filetype = $movefile['type'];
            $filename = $movefile['file'];
            $wp_upload_dir = wp_upload_dir();
            $attachment = array(
                'guid' => $wp_upload_dir['url'] . '/' . basename( $filename ),
                'post_mime_type' => $wp_filetype,
                'post_title' => preg_replace('/\.[^.]+$/', '', basename($filename)),
                'post_content' => '',
                'post_status' => 'inherit'
            );
            $attach_id = wp_insert_attachment( $attachment, $filename);
            echo '<br>';
            //return $attach_id;
            //var_dump($movefile);
            print_r($movefile);
            //wp_die('end');
        } else {
            return 'fail';      
        }
}

The file name is being grabbed properly but when I do a print_r on $movefile, I get the following error: Array ( [error] => Specified file failed upload test. )

No file is added to the media library.

What do I need to do to my code for it to pass the test?

Here is a screenshot of the settings page for my theme: http://pasteboard.co/yFck7LW.png