There are several reasons:
You room is a special accommodation room. There are various reasons why a room is considered special and must be held for specific students. These rooms cannot be retained and will not be available during the assignment period.
You are living in freshman housing. Freshman are required to move to upperclassmen housing, so that new freshman can move into their spaces.
You haven’t completed your contract renewal application. You must first complete the contract renewal application before you can retain your room.
You haven’t completed your pre-payment and it hasn’t been waived. You must also complete the pre-payment if it wasn’t waived.
You are living in Jefferson or the Quad. Students in the Quad and Jefferson are not permitted to retain their spaces to give freshman the option to select those spaces.