stairproblem

I"m running into an early game issue where my characters don't seem to be able to climb or descend staircases. No icon appears above these locations but I know that they must be usable considering most walkthroughs I"ve seen show these locations being used. Currently I've made it to the Old Watcher mission but am now trapped storywise because I cannot enter the basement. I've run into a similar issue when trying to infiltrate the castle of the Lord of the first town. I can enter the castle fine but once I'm in a room that requires that I go up or down I'm stuck on that floor. Help?