Issue with prepared statement

Hello,

I am trying to create a prepared statement for the following query in
MySQL:

INSERT IGNORE INTO foo (group, value) (SELECT 101, value FROM bar
WHERE value LIKE '%something%');

So far my Perl code looks something like this:

my $group = 101;
my $pattern = '%something%';
my $query = 'INSERT IGNORE INTO foo (group, value) (SELECT ?, value
FROM bar WHERE value LIKE ?);';
my $sth = $dbh->prepare($query);
$sth->execute($id, $pattern) or die($sth->errstr);

It does not insert anything into the table foo even though there are
values in table bar that match the pattern. So my question is: what am
I doing wrong. I have other, simpler prepared queries in my program
that work just fine but this one does not do anything and does not
trigger any error as far as I can see.

Are ? parameters allowed in a nested SELECT?
Are they allowed not in the WHERE clause?
Are they allowed with the LIKE operator?

Thanks in advance for your help.

Tom