Select posts (Students) with meta_key 'birthday' value between two dates

Hi All,

I’m currently working on a WordPress website for a lower school. They want to have a widget that displays all the students who have their birthday that week. I have made a meta_key with value 2008-06-29.

I’m trying the following.

$args = array(
	'post_type' => 'student',
	'posts_per_page' => -1,
	'meta_query' => array(
		array(
			'key'     => '_birthday',
			'value'   => array( $start, $end ),
			'compare' => 'BETWEEN',
		),
	),
	'order' => 'ASC',
	'orderby' => 'meta_value',
	'meta_key' => '_birthday'
);

Start = %-06-24
End = %-06-30

But that isn’t working. Does someone know how to get these posts?

Many thanks in advance.