Dreambox is the most advanced satellite receiver there is. By being so advanced (new generation of sat receiver) it contains as part of the software much encoder information which previously required a card to be inserted in the cam slot. Perhaps many of those codes need updating? Or you need to get the dreambox itself updated to the latest version. Is yours a version that has to be linked to your telephone line router to operate the encryption via the Internet?
Do a google search for dreambox and the model/version you are using and see if in the results you come across any web sites where others are discussing about it possibly in specialist forums or chatrooms.