BP- Auto Group Join Issue

I receive the following error message after registering a new account.

Warning: in_array() expects parameter 2 to be array, string given in /home1/newsigan/public_html/wp-content/plugins/bp-auto-group-join/includes/bp-auto-group-join-base-class.php on line 76

the line in question appears like this:

if( in_array($user_member_type, $get_mt) ){

The block looks like this:

);
if ( bp_has_groups( $groups_args ) ) :
while ( bp_groups() ) : bp_the_group();
$group_id = bp_get_group_id();
$get_settings = groups_get_groupmeta($group_id, ‘aj_new_registrations’, true);
if($get_settings == ‘all_members’){
// add as member
groups_accept_invite($user_id, $group_id);
}else{
$get_mt = groups_get_groupmeta($group_id, ‘aj_new_registrations_mt’, true);
$user_member_type = bp_get_member_type( $user_id );
if( in_array($user_member_type, $get_mt) ){
// add as member
groups_accept_invite($user_id, $group_id);
}

Any ideas?