When in backend I create an url to invite somebody I get this:

http://www.acpjt.cat/administrator/index.php?option=com_communitysurveys&view=surveys&task=take_survey&key=nDn1Q5fFPKXdbo6GnESaxuMGifCeLxHP

Obviously, the correct path can't include the administrator directory.
I should get this:
http://www.acpjt.cat/index.php?option=com_communitysurveys&view=survey&task=take_survey&key=SQ8cXkinf2UBnmICovGatHuK4evaNg2f&Itemid=720

Any help?

Thanks in advance