alchymyth on "Adding footer sidebar"

do not copy the contents of functions.php from the parent theme into the child theme; only add new or pluggable functions or filter etc;

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

i.e. try to start a new empty functions.php in your child theme, starting with <?php right at the start in the first line, and just with your sidebar codes