Yes, Sago has that problem. If you you are a rogue and a caster. The NWN engine gets confused because it was coded to look at things in the wrong order. It sees you have UMD and applies that skill when you try and use the scroll. It should first notice Sago is a cleric and let him cast the cleric scrolls with no check. It doesn't though, all scrolls are lumped in and use the UMD skill.