I have a baffling problem with my mod that I cannot reproduce myself, but somehow affects a minority of users. Even if they are running only my mod and do a clean save. Its to do with the vanilla quest called DialogueFollower. This is the quest that is used most, if not all, of the time to allow any vanilla companion to follow the player. Part of my mod adds additional AI to the AI stack in the Follower Alias belonging to this quest. This is where the problem lies...

What happens, judging from the complaints I receive, the vanilla AI follow package PlayerFollowerPackage still runs but not the new ones I added. I know this is so because I once added a condition that prevented that particular AI from running, so another AI package takes over. This worked fine for most people, but for these few users a major problem. The follower will default to the AI stack on the NPC, not the Alias - which means they will wander off home. I have since removed this condition, and they report the problem is no longer apparent. But, the other AI packages I added are still not running.

I wonder if its another quest doing this - that somehow switches the follow routine to another quests follower routine. This would make sense as special new follower dialogue can run (for quests storylines), instead of the same old ones. So I also checked which quests use that particular AI package (PlayerFollowerPackage) and there is only one other - to do with a quest involving the Blades.

So why it it most can use my mod, and some cannot?

If you want to look at my mod, its here (two plugins), although I'll be updating it over the coming days >>>>

http://skyrim.nexusmods.com/downloads/file.php?id=11193

I better add that in my mod "Horses For Followers" that the ownership of the horses is set to PlayerFaction. In earlier versions it was set to CurrentFollowerFaction. People didn't like the red steal flag showing (since the player pays) or getting a blackeye from Lydia if the player mounted her horse accidently. So I'm working under the assumption that all follower's are playerFaction members. Either way, since they all follow the player - and there is only one package for that - they should be filling the Follower Alias and run the new AI packages too. But they don't for all people.

Could the problem be this the Race Condition described here (http://www.creationkit.com/Quest_Alias_Tab#Checkboxes:) ?
Which would mean its not working, and the My quest is Start enabled and the checkbox for Allow Reserved is not checked and just greyed out. I have seen this greyed and check on vanilla quests. So it could be broken for us.

For what it's worth, I've had a couple people complain that even basic stuff in my mod like new dialogue wouldn't work for them, and it turned out they were using older copies of Skyrim, like version 1.1. Have you verified that these folks having problems with your mod are using the latest version of the game?

same here with the dialogue problem. It even affected me at one stable, so it does seem that certain times problems occur - maybe a vanilla quest taking over. One or two did have old versions but not all. Almost everyday there is someone saying their companions will not ride the horse. I know a few unpacked the scripts, so the updates wouldn't run. As far as I know, the game will check the data subfolders before the BSA. But it does appear to be a consistant problem. So I tried CurrentFollowerFaction to begin with- which should net every follower. Then tried PlayerFaction which one person said prevented Aela mounting but not Lydia. Some are saying not any will mount. I quess I have to get them to send me game saves to nail this problem.