i need help tracking down a phantom issue that's really starting to drive me insane...

in my Smack The Smith mod, you need to acquire a couple of items to proceed.

i check for these items in a player alias script:

Event OnItemAdded ( Form akItemBase, Int aiItemCount, ObjectReference akItemRef, ObjectReference akSourceCont )    if ( akItemBase == Nails )        if ( SmackTheSmith.GetStage () == 500 )            if ( Game.GetPlayer ().GetItemCount ( Nails ) >= 500 )                if SmackTheSmith.IsObjectiveDisplayed ( 550 )                    SmackTheSmith.            SetObjectiveCompleted     ( 550, true )                    SmackTheSmith.            SetObjectiveDisplayed     ( 550, false )                    SmackTheSmith.            SetObjectiveDisplayed     ( 551, true, true )                endif            endif        endif;    elseif (...)    endifendEventEvent OnItemRemoved ( Form akItemBase, Int aiItemCount, ObjectReference akItemRef, ObjectReference akTargetCont )    if ( ( akItemBase == Nails ) && ( akTargetCont != ( Smack as ObjectReference ) ) )        if ( GetRef ().GetItemCount ( Nails ) < 500 )            if ( SmackTheSmith.GetStage () == 500 )                if SmackTheSmith.IsObjectiveDisplayed ( 551 )                    SmackTheSmith.        SetObjectiveDisplayed     ( 551, false )                    SmackTheSmith.        SetObjectiveDisplayed    ( 550, true, true )                endif            endif        endif ;    elseif (...)    endifendEvent

...but there's a part of users, for whom this just doesn't fire, no matter what i try.

they acquire the "nails", but the objective ("deliver nails") never displays.

...and worse:

to deliver the items, a conditioned "here's your nails"-dialogue line should be available

as a safety measure, i stripped down it's conditions to what's absolutely necessary: actor id, quest stage, item count in player's inventory (plus if a certain ref is disabled, which definitely is at the time) -

so, if just player has the items, this should actually appear even if above script never fired - for affected users though, it doesn't.

i'm 1000% out of clue with this. it all works fine for a vast majority of users, and i never could get that issue to appear in any of my games no matter what i tried -

checked and re-checked it all a billion times, but just can't find _anything_ that could cause this.

a couple of things i could rule out so far:

.) the player alias with the script and it's holding quest as well as the quest with the dialogue are up and running at the time

.) all properties are properly filled of course

.) quest stage is right what it should be

.) items are in player's inventory at the time, not consoled there and showing up on console

.) i had a user with that issue with 7 mods installed, nothing affecting inv management or anything, so pretty sure no mod conflict

any idea very appreciated

(...http://steamcommunity.com/sharedfiles/filedetails/?id=306323341&searchtext=smack+the+smith with all script source in the bsa btw, if anybody wants to take a closer look)