I think I’ve talked some about this one before, but it doesn’t hurt to mention clearly. There’s currently a bug in the CK that prevents serious quest-modding.
From the Creation Kit Bug Thread on the official forum: “Patch 1.6 has introduced a critical bug relating to dialogue. Attempting to modify vanilla dialogue in any way or creating your own will result in it becoming completely broken, with the audio and lip sync failing to work. It also causes any attached result script to fail to function. This is a very serious issue which affects almost all CK users.”
It’s most disturbing, since it’s the new NavMesh-bug, but I have things to do while they fix it, and I’m sure they will fix it asap too.