Not enough information to go on here on how you are trying into enter these deep dungeons.

Are you just locked out? Have you done the quest to unlock them?

Does everyone in your fixed party have all the requirements?

Are you entering on a new save slot or is it a saved one one that's from a previous run?

Coming in the forums and ranting with little details on the issue to make a request for an answer, you must be just wanting to let off steam and screw any real answers as to why you can't enter with a fixed party in either deep dungeon.