Why can't I assign deck?

Hi all. I am using Ram to do gravity design and try to assign deck. However, I can assign deck to all the floors except one of them which has the same structural layout as others. I am sure that there is no deck assigned. Also Tried to delete the deck several times. Therefore, I just want to know why it is happening and how I can fix it? Thanx

Mar 15 Gravity Design.rss