Using Smartbuff to create and apply Soulstone to myself.
After creating soulstone using Smartbuff, I get the following:

14x SmartBuff\SmartBuff-4.3a.lua:2236 attempt to concatenate local "icon" (a nil value)
SmartBuff\SmartBuff-4.3a.lua:2236 in function "SMARTBUFF_SetMissingBuffMessage"
SmartBuff\SmartBuff-4.3a.lua:2138 in function "SMARTBUFF_BuffUnit"
SmartBuff\SmartBuff-4.3a.lua:1592 in function "SMARTBUFF_Check"
SmartBuff\SmartBuff-4.3a.lua:619 in function "SMARTBUFF_OnUpdate"
<string>:"*:OnUpdate":1: in function <string>:"*:OnUpdate":1

Locals:
unit = "player"
subgroup = 0
mode = 1
spell = nil
bs = <table> {
 RBTime = 0
 IgnoreList = <table> {}
 COut = 1
 EnableS = true
 SelfNot = false
 EnableG = false
 SelfOnly = 1
 AddList = <table> {}
 Reminder = 1
 RH = false
 ManaLimit = 0
}
buff = "Soulstone"
buffname = nil
buffnS = nil
uc = "WARLOCK"
ur = "NONE"
un = "Sanist"
uct = "Humanoid"
ucf = ""
r = nil
i = nil
bt = nil
cd = -205389.839
cds = 0
charges = nil
handtype = ""
bExpire = false
isPvP = true
bufftarget = "Sanist"
rbTime = 20
bUsable = true
time = 205389.839
cBuff = <table> {
 CanCharge = false
 Type = "ITEMGROUP"
 DurationS = 900
 Exclude = "Soulstone Resurrection"
 BuffS = "Soulstone"
}
iId = nil
iSlot = -1
(for generator) = <func> =[C]:-1
(for state) = <table> {
 1 = "Fel Armor"
 2 = "Demon Armor"
 3 = "Soul Link"
 4 = "Unending Breath"
 5 = "Shadow Ward"
 6 = "Dark Intent"
 7 = "Life Tap"
 8 = "Soul Harvest"
 9 = "Soulstone"
 10 = "Create Soulstone"
 11 = "Create Healthstone"
}
(for control) = 9
i = 9
buffnS = "Soulstone"
cBlacklist = <table> {}
O = <table> {
 ToggleAutoCombat = false
 AutoSwitchTemplateInst = false
 BuffTarget = false
 SplashY = -99.999967667228
 MMCPosX = -44.372615427091
 IgnoreList = <table> {}
 ToggleSubGrpChanged = false
 SplashX = 99.999994658064
 ToggleMsgNormal = false
 AutoTimer = 5
 ToggleGrp = <table> {}
 AutoSwitchTemplate = true
 AntiDaze = true
 RebuffTimer = 20
 ToggleAutoSplash = true
 BuffPvP = false
 ColSplashFont = <table> {}
 UpgradeToDualSpec = true
 OldWheelDown = "CAMERAZOOMOUT"
 LastTemplate = "Solo"
 AddList = <table> {}
 Toggle = true
 OldWheelUp = "CAMERAZOOMIN"
 ShowMiniGrp = false
 BlacklistTimer = 5
 Debug = false
 MinCharges = 0
 UISync = true
 HideMmButton = false
 ToggleAutoSound = false
 BuffInCities = true
 MMCPosY = -93.681158761987
 ToggleMsgError = false
 ToggleMsgWarning = false
 CompMode = false
 SplashDuration = 2
 LinkGrpBuffCheck = true
 CurrentFont = 9
 ToggleAuto = true
 InShapeshift = true
 CheckCharges = false
 HideSAButton = true
 ScrollWheelDown = true
 ToggleAutoChat = false
 LinkSelfBuffCheck = true
 ScrollWheelUp = true
 InCombat = true
}
isShapeshifted = false
sShapename = nil
B = <table> {
 1 = <table> {}
 2 = <table> {}
}
CS = <func> @..\SmartBuff.lua:241
isSetBuffs = false
cBuffs = <table> {
 1 = <table> {}
 2 = <table> {}
 3 = <table> {}
 4 = <table> {}
 5 = <table> {}
 6 = <table> {}
 7 = <table> {}
 8 = <table> {}
 9 = <table> {}
 10 = <table> {}
 11 = <table> {}
}
cBuffIndex = <table> {
 Fel Armor = 1
 Soulstone = 9
 Shadow Ward = 5
 Unending Breath = 4
 Soul Link = 3
 Create Healthstone = 11
 Create Soulstone = 10
 Soul Harvest = 8
 Life Tap = 7
 Demon Armor = 2
 Dark Intent = 6
}
GetBuffSettings = <func> @..\SmartBuff.lua:256
sPlayerClass = "WARLOCK"
isMounted = nil
isCombat = false
sMsgWarning = "Global cooldown!"
cBuffTimer = <table> {
 player = <table> {}
}
currentUnit = nil
currentSpell = nil
tLastCheck = 205389.839
maxSkipCoolDown = 3