wordpress - PHP — Undefined Variable with $_GET Test -

wordpress - PHP — Undefined Variable with $_GET Test -

i have form in sidebar on next wp site — http://www.mattpealing-server.co.uk/~devchewengco/

here part of code i'm using results page:

<?php if (isset($_get['appliancetype']) || isset($_get['brand'])) : // search filter form ?> <?php query_posts($query_string . '&orderby=title&order=asc') ?> <?php get_template_part('loop', 'feed-products' ); ?> <?php wp_reset_query(); ?> <?php else : // display categories default ?> <?php get_template_part('include', 'feed-categories-products' ); ?> <?php endif; ?>

but statement returning false. originally, had without isset() function, giving me undefined variable errors

can see i'm doing wrong?

just found in url have undefined warning. have use:

isset($_get['brand']) // using 'brand'

php wordpress forms variables get