Wildcard / regexp search over non analyzed fields

Hi out there,

i try to send some wildcard/regexp querys to ElasticSearch - but somehow the requests fail.
I am using
[version] => Array
[number] => 2.2.1
[lucene_version] => 5.4.1

and my query looks like
$Query = array(
"query" => array(
"bool" => array(
"must" => array(
"wildcard" => array( "category" => "A?"),
"filter" => array (
"match" => array( 'active' => '1'),

I expect to get all documents where the category is named like "AA", "AB", AC" - but unfortunately i always get an empty result, without any error message.

Can somebody help me finding out what i am missing?

After playing around for a while i was able to figure out that ES stores all strings in lowercase, so simply using "a?" instead of "A?" solved my problem.

Would be nice to have that a little bit clearer in the terms documentation.