Link to the demo in just a sec, here's some background:
This takes place at the very end of this section of the main quest. The NPC in question has 6 event pages, all kick off properly except page 3. Here's how it works:
On page 2, he'll send you to look for someone. You go and find the guy, then have the option of moving to stage 2, or going back to NPC. If you go back to NPC, page 6 will kick off and you move to stage 2.
Again, after completion, you have the option of continuing or returning. If you return, page 5 kicks off and you move to stage 3.
After completion, same deal, page 4 kicks off and you go to stage 4.
After completion of the final stage, you have to return to NPC, but page 3 never kicks off. Tried rearranging the conditions, etc., just can't get the guy to talk. Note that at any point you complete more than one stage, the necessary event page has dialogue indicating your completion and the next step you need to take, if any.
You can complete the whole thing after he gives you the quest and only talk to him at the end which would kick off page 6 and contain all the necessary stuff to wrap up your business there.
If you prefer the long route, which would be talking to him at any point between starting and completing the quest line, you can only finish stage 4, and he'll stonewall you at that point.
If anyone would be so kind as to take a look, there's a small demo, load the save game, new game won't work as I've removed everything that isn't necessary to this exact point in the game, or pull it up in the editor and see if you can figure out where I went wrong.
http://mixitup.us/Downloads/Demo.rar