NPC Cannot Be My Follower

Not all NPCs can be made into followers; this is just the way Skyrim is set up. There are two conditions that the follower quest checks and must be met in order for the follower dialogue to appear. The first is the voice type. The NPC must have a voice type that is a Default NPC Voice Type (which is why the command won't work on any of the unique voice NPCs). The second condition is that they cannot be a Jarl (JobJarlFaction = 0). Trying to force someone to be a follower will not work if a NPC fails either one of these two conditions. I suggest saving before you try and reload if that NPC doesn't work.

For certain NPCs, the follow options may not appear until you reset the NPCs dialogue options.
Open the console (after you turn them), click on the NPC and type the following lines into the console:

Disable
Enable 



I suggest trying to use this mod to expand the number of voice types that can become followers.

http://www.nexusmods.com/skyrim/mods/36913
The More Follower Voices Mod:

   - Expands almost all Skyrim voices to have voiced follower dialogue.
   - Expands Khajiit voices to have voiced marriage dialogue.
   - 100% Lore-friendly, no NPC's have been edited to be followers.
   - Comes with Demo NPC followers that can be spawned by the player.
   - 100% Compatible with all -popular- follower mods, FCO, & Hearthfire & Familiar Faces