I am guessing you have (SPOILER)freed rinoa, from the sorceress memorial, been to edeas house been to the flower field, then returned to the palace, speaked with the pres. Then after all that flied straigt into the lunitic pandora with the ragnorak.

If you have done all that and still are not able to get in, then you may have a glitch in the game. Sorry if that is to case.