CKFinder doesn't work on multiple domains

I'm integrating CKEditor with CKFinder. My resource files (JS, CSS, Images) are on a subdomain(Including CKEDITOR and CKFINDER). When i try to use CKFinder it throws that error:

Permission denied for <http://resources.****>... if (parentWindow['CKEDITOR'])

EDIT: I saw in an other topic that this is accepted as a XSS atack... Please, give me some ideas, i can't change my project architecture.