I'm not entirely sure what you mean, but this is the fragment that sets the stage to 10
"Oh, thank you so much. It's been taken to Reachwind Eyrie. Please hurry! I'll give you twice what it's worth!"
GetOwningQuest().SetObjectiveDisplayed(10)
GetOwningQuest().SetStage(10)
You have the SEQ file, I'm assuming? Also, you don't need the SetObjectiveDisplayed in the dialogue fragment. Put it in the quest stage fragment for stage 10.
I don't know what could be wrong... Huh. I just had a similar issue - it all seemed right, but it wasn't working. I'm afraid I can't help you with this one. Sorry.
Ok, that makes sense. I was just following what the tutorial said to do here:

I meant to post this too, but for reason it got deleted. It is the papyrus fragments for stage 10 under quest stage. It doesn't work to enable the thief alias though:
SetObjectiveDisplayed(10)
Alias_Thief.GetReference().Enable()
DungeonMarkre.AddToMap()
I bet this is all caused by something stupid. Like when I made my first bookshelf, it didn't work and I remade it 5 times and spent hours troubleshooting until I figured out that I had to leave and re-enter the cell to get it to work.