[circonian]

I tested that once, I'm not sure but if I remember correctly I think that you have to gain skill in it during that game session/reload before that API will work.

I'm guessing that your doing this just to save/load skills into the skill bar. You don't need skillType, skillLineIndex, LineAbilityIndex. Just use the abilityId to get the real abilityIndex and use it to load the skill:

local abilityId = GetSlotBoundId(slotNum)
-- save it, then to reload:
local hasProgression, progressionIndex = GetAbilityProgressionXPInfoFromAbilityId(abilityId)
--[[ These two steps ensure you load the correct ability because the 
abilityId, progressionIndex, and ..a lot of things change every time 
an ability ranks up or is morphed. This way even if the saved abilityId 
is an "old" lower rank, unmorphed, or different morph the correct ability 
will still be loaded.
--]]
local unMorphedName, morphChoice, rank = GetAbilityProgressionInfo(progressionIndex)
local morphedName, texture, abilityIndex = GetAbilityProgressionAbilityInfo(progressionIndex, morphChoice, rank)
-- and note the above abilityIndex is NOT the same abilityIndex as this:
-- local skillType, skillIndex, abilityIndex = GetSkillAbilityIndicesFromProgressionIndex(progressionIndex)
 
 
CallSecureProtected("SelectSlotAbility", abilityIndex, slotNum)