How to create a new subfolder to an asset with plugin
I’ve had the problem with storeFolder() that it doesn’t create a folder that is accessible via the control panel or the file system.

I find createFolder() much easier to use and it did what I expected:

$response = craft()-&gt;assets-&gt;createFolder($parentFolderId, $folderName);
$folderId = $response-&gt;getResponseData()['folderId'];